Move most of the peculiar argument handling for external calls into the parser (#13089)

# Description

We've had a lot of different issues and PRs related to arg handling with
externals since the rewrite of `run-external` in #12921:

- #12950
- #12955
- #13000
- #13001
- #13021
- #13027
- #13028
- #13073

Many of these are caused by the argument handling of external calls and
`run-external` being very special and involving the parser handing
quoted strings over to `run-external` so that it knows whether to expand
tildes and globs and so on. This is really unusual and also makes it
harder to use `run-external`, and also harder to understand it (and
probably is part of the reason why it was rewritten in the first place).

This PR moves a lot more of that work over to the parser, so that by the
time `run-external` gets it, it's dealing with much more normal Nushell
values. In particular:

- Unquoted strings are handled as globs with no expand
- The unescaped-but-quoted handling of strings was removed, and the
parser constructs normal looking strings instead, removing internal
quotes so that `run-external` doesn't have to do it
- Bare word interpolation is now supported and expansion is done in this
case
- Expressions typed as `Glob` containing `Expr::StringInterpolation` now
produce `Value::Glob` instead, with the quoted status from the expr
passed through so we know if it was a bare word
- Bare word interpolation for values typed as `glob` now possible, but
not implemented
- Because expansion is now triggered by `Value::Glob(_, false)` instead
of looking at the expr, externals now support glob types

# User-Facing Changes

- Bare word interpolation works for external command options, and
otherwise embedded in other strings:
  ```nushell
  ^echo --foo=(2 + 2) # prints --foo=4
  ^echo -foo=$"(2 + 2)" # prints -foo=4
  ^echo foo="(2 + 2)" # prints (no interpolation!) foo=(2 + 2)
  ^echo foo,(2 + 2),bar # prints foo,4,bar
  ```

- Bare word interpolation expands for external command head/args:
  ```nushell
  let name = "exa"
  ~/.cargo/bin/($name) # this works, and expands the tilde
  ^$"~/.cargo/bin/($name)" # this doesn't expand the tilde
  ^echo ~/($name)/* # this glob is expanded
  ^echo $"~/($name)/*" # this isn't expanded
  ```

- Ndots are now supported for the head of an external command
(`^.../foo` works)

- Glob values are now supported for head/args of an external command,
and expanded appropriately:
  ```nushell
  ^("~/.cargo/bin/exa" | into glob) # the tilde is expanded
  ^echo ("*.txt" | into glob) # this glob is expanded
  ```

- `run-external` now works more like any other command, without
expecting a special call convention
  for its args:
  ```nushell
  run-external echo "'foo'"
  # before PR: 'foo'
  # after PR:  foo
  run-external echo "*.txt"
  # before PR: (glob is expanded)
  # after PR:  *.txt
  ```

# Tests + Formatting
Lots of tests added and cleaned up. Some tests that weren't active on
Windows changed to use `nu --testbin cococo` so that they can work.
Added a test for Linux only to make sure tilde expansion of commands
works, because changing `HOME` there causes `~` to reliably change.

- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting
- [ ] release notes: make sure to mention the new syntaxes that are
supported

crates/nu-cli/src/syntax_highlight.rs

@@ -138,6 +138,7 @@ impl Highlighter for NuHighlighter {
 
                 FlatShape::Filepath => add_colored_token(&shape.1, next_token),
                 FlatShape::Directory => add_colored_token(&shape.1, next_token),
+                FlatShape::GlobInterpolation => add_colored_token(&shape.1, next_token),
                 FlatShape::GlobPattern => add_colored_token(&shape.1, next_token),
                 FlatShape::Variable(_) | FlatShape::VarDecl(_) => {
                     add_colored_token(&shape.1, next_token)
@@ -452,15 +453,17 @@ fn find_matching_block_end_in_expr(
                 }
             }
 
-            Expr::StringInterpolation(exprs) => exprs.iter().find_map(|expr| {
-                find_matching_block_end_in_expr(
-                    line,
-                    working_set,
-                    expr,
-                    global_span_offset,
-                    global_cursor_offset,
-                )
-            }),
+            Expr::StringInterpolation(exprs) | Expr::GlobInterpolation(exprs, _) => {
+                exprs.iter().find_map(|expr| {
+                    find_matching_block_end_in_expr(
+                        line,
+                        working_set,
+                        expr,
+                        global_span_offset,
+                        global_cursor_offset,
+                    )
+                })
+            }
 
             Expr::List(list) => {
                 if expr_last == global_cursor_offset {