Add command_palette_hooks crate (#8398)

This PR introduces a new `command_palette_hooks` crate that contains the
types used to hook into the behavior of the command palette.

The `CommandPaletteFilter` was previously extracted to the `copilot`
crate in #7095, solely because that was the earliest ancestor of the
crates that depended on it.

The `CommandPaletteInterceptor` was still defined in `command_palette`
itself.

Both of these types were consumed by other crates wanting to influence
the behavior of the command palette, but required taking a dependency on
the entire `command_palette` crate in order to gain access to these
hooks.

By moving them out into their own crate, we can improve the compile
order and make crates like `vim` able to begin building sooner without
having to wait for `command_palette` to finish compiling.

Here's a comparison of the compilation graph before and after (ignore
the timings):

#### Before

<img width="332" alt="Screenshot 2024-02-25 at 12 42 29 PM"
src="https://github.com/zed-industries/zed/assets/1486634/a57c662e-fbc2-41ab-9e30-cca17afa6c73">

#### After

<img width="362" alt="Screenshot 2024-02-25 at 12 51 15 PM"
src="https://github.com/zed-industries/zed/assets/1486634/c1a6d29c-b607-4604-8f1b-e5d318bf8849">

Release Notes:

- N/A

Cargo.lock

@@ -2214,7 +2214,7 @@ dependencies = [
  "anyhow",
  "client",
  "collections",
- "copilot",
+ "command_palette_hooks",
  "ctor",
  "editor",
  "env_logger",
@@ -2237,6 +2237,14 @@ dependencies = [
  "zed_actions",
 ]
 
+[[package]]
+name = "command_palette_hooks"
+version = "0.1.0"
+dependencies = [
+ "collections",
+ "gpui",
+]
+
 [[package]]
 name = "concurrent-queue"
 version = "2.2.0"
@@ -2296,6 +2304,7 @@ dependencies = [
  "async-tar",
  "clock",
  "collections",
+ "command_palette_hooks",
  "fs",
  "futures 0.3.28",
  "gpui",
@@ -11002,7 +11011,7 @@ dependencies = [
  "async-trait",
  "collections",
  "command_palette",
- "copilot",
+ "command_palette_hooks",
  "editor",
  "futures 0.3.28",
  "gpui",