Allow plugins to report their own version and store it in the registry (#12883)

# Description

This allows plugins to report their version (and potentially other
metadata in the future). The version is shown in `plugin list` and in
`version`.

The metadata is stored in the registry file, and reflects whatever was
retrieved on `plugin add`, not necessarily the running binary. This can
help you to diagnose if there's some kind of mismatch with what you
expect. We could potentially use this functionality to show a warning or
error if a plugin being run does not have the same version as what was
in the cache file, suggesting `plugin add` be run again, but I haven't
done that at this point.

It is optional, and it requires the plugin author to make some code
changes if they want to provide it, since I can't automatically
determine the version of the calling crate or anything tricky like that
to do it.

Example:

```
> plugin list | select name version is_running pid
╭───┬────────────────┬─────────┬────────────┬─────╮
│ # │      name      │ version │ is_running │ pid │
├───┼────────────────┼─────────┼────────────┼─────┤
│ 0 │ example        │ 0.93.1  │ false      │     │
│ 1 │ gstat          │ 0.93.1  │ false      │     │
│ 2 │ inc            │ 0.93.1  │ false      │     │
│ 3 │ python_example │ 0.1.0   │ false      │     │
╰───┴────────────────┴─────────┴────────────┴─────╯
```

cc @maxim-uvarov (he asked for it)

# User-Facing Changes

- `plugin list` gets a `version` column
- `version` shows plugin versions when available
- plugin authors *should* add `fn metadata()` to their `impl Plugin`,
but don't have to

# Tests + Formatting

Tested the low level stuff and also the `plugin list` column.

# After Submitting
- [ ] update plugin guide docs
- [ ] update plugin protocol docs (`Metadata` call & response)
- [ ] update plugin template (`fn metadata()` should be easy)
- [ ] release notes

crates/nu-plugin-protocol/src/lib.rs

@@ -23,7 +23,7 @@ pub mod test_util;
 
 use nu_protocol::{
     ast::Operator, engine::Closure, ByteStreamType, Config, LabeledError, PipelineData,
-    PluginSignature, ShellError, Span, Spanned, Value,
+    PluginMetadata, PluginSignature, ShellError, Span, Spanned, Value,
 };
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
@@ -119,6 +119,7 @@ pub struct ByteStreamInfo {
 /// Calls that a plugin can execute. The type parameter determines the input type.
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub enum PluginCall<D> {
+    Metadata,
     Signature,
     Run(CallInfo<D>),
     CustomValueOp(Spanned<PluginCustomValue>, CustomValueOp),
@@ -132,6 +133,7 @@ impl<D> PluginCall<D> {
         f: impl FnOnce(D) -> Result<T, ShellError>,
     ) -> Result<PluginCall<T>, ShellError> {
         Ok(match self {
+            PluginCall::Metadata => PluginCall::Metadata,
             PluginCall::Signature => PluginCall::Signature,
             PluginCall::Run(call) => PluginCall::Run(call.map_data(f)?),
             PluginCall::CustomValueOp(custom_value, op) => {
@@ -143,6 +145,7 @@ impl<D> PluginCall<D> {
     /// The span associated with the call.
     pub fn span(&self) -> Option<Span> {
         match self {
+            PluginCall::Metadata => None,
             PluginCall::Signature => None,
             PluginCall::Run(CallInfo { call, .. }) => Some(call.head),
             PluginCall::CustomValueOp(val, _) => Some(val.span),
@@ -309,6 +312,7 @@ pub enum StreamMessage {
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub enum PluginCallResponse<D> {
     Error(LabeledError),
+    Metadata(PluginMetadata),
     Signature(Vec<PluginSignature>),
     Ordering(Option<Ordering>),
     PipelineData(D),
@@ -323,6 +327,7 @@ impl<D> PluginCallResponse<D> {
     ) -> Result<PluginCallResponse<T>, ShellError> {
         Ok(match self {
             PluginCallResponse::Error(err) => PluginCallResponse::Error(err),
+            PluginCallResponse::Metadata(meta) => PluginCallResponse::Metadata(meta),
             PluginCallResponse::Signature(sigs) => PluginCallResponse::Signature(sigs),
             PluginCallResponse::Ordering(ordering) => PluginCallResponse::Ordering(ordering),
             PluginCallResponse::PipelineData(input) => PluginCallResponse::PipelineData(f(input)?),