Integrated Language Server (#10723)

# Description

This commit integrates a language server into nushell so that IDEs don't
have to convert CLI option back and forth.

- fixes https://github.com/nushell/vscode-nushell-lang/issues/117
- fixes https://github.com/jokeyrhyme/nuls/issues/8

Tracking tasks


- [x]
[textDocument/hover](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_hover)
-> `nu --ide-hover`
- [x]
[textDocument/completion](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_completion)
-> `nu --ide-complete`
- [x]
[textDocument/definition](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_definition)
-> `nu --ide-goto-def`
- ~~[ ]
[textDocument/didChange](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_didChange),
[textDocument/didClose](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_didClose),
and
[textDocument/didOpen](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_didOpen)~~
(will be done in a follow-up PR)
- ~~[ ]
[textDocument/inlayHint](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_inlayHint)
-> `nu --ide-check`~~ (will be done in a follow-up PR)
- ~~[ ]
[textDocument/publishDiagnostics](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_publishDiagnostics)
-> `nu --ide-check`~~ (will be done in a follow-up PR)
- ~~[ ]
[workspace/configuration](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspace_configuration)~~
(will be done in a follow-up PR)
- ~~[ ]
[workspace/didChangeConfiguration](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspace_didChangeConfiguration)~~
(will be done in a follow-up PR)


# User-Facing Changes

The command line options `--lsp` will start a LSP server.

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
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- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use std testing; testing run-tests --path
crates/nu-std"` to run the tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
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-->

src/command.rs

@@ -37,7 +37,7 @@ pub(crate) fn gather_commandline_args() -> (Vec<String>, String, Vec<String>) {
             #[cfg(feature = "plugin")]
             "--plugin-config" => args.next().map(|a| escape_quote_string(&a)),
             "--log-level" | "--log-target" | "--testbin" | "--threads" | "-t"
-            | "--include-path" | "--ide-goto-def" | "--ide-hover" | "--ide-complete"
+            | "--include-path" | "--lsp" | "--ide-goto-def" | "--ide-hover" | "--ide-complete"
             | "--ide-check" => args.next(),
             _ => None,
         };
@@ -108,6 +108,7 @@ pub(crate) fn parse_commandline_args(
                 call.get_flag(engine_state, &mut stack, "table-mode")?;
 
             // ide flags
+            let lsp = call.has_flag("lsp");
             let include_path: Option<Expression> = call.get_flag_expr("include-path");
             let ide_goto_def: Option<Value> =
                 call.get_flag(engine_state, &mut stack, "ide-goto-def")?;
@@ -193,6 +194,7 @@ pub(crate) fn parse_commandline_args(
                 ide_goto_def,
                 ide_hover,
                 ide_complete,
+                lsp,
                 ide_check,
                 ide_ast,
                 table_mode,
@@ -229,6 +231,7 @@ pub(crate) struct NushellCliArgs {
     pub(crate) execute: Option<Spanned<String>>,
     pub(crate) table_mode: Option<Value>,
     pub(crate) include_path: Option<Spanned<String>>,
+    pub(crate) lsp: bool,
     pub(crate) ide_goto_def: Option<Value>,
     pub(crate) ide_hover: Option<Value>,
     pub(crate) ide_complete: Option<Value>,
@@ -298,7 +301,12 @@ impl Command for Nu {
                 "start with an alternate environment config file",
                 None,
             )
-            .named(
+            .switch(
+               "lsp",
+               "start nu's language server protocol",
+               None,
+            )
+           .named(
                 "ide-goto-def",
                 SyntaxShape::Int,
                 "go to the definition of the item at the given position",
@@ -309,7 +317,7 @@ impl Command for Nu {
                 SyntaxShape::Int,
                 "give information about the item at the given position",
                 None,
-            )
+             )
             .named(
                 "ide-complete",
                 SyntaxShape::Int,