Introduce settings profiles (#35339)

Settings Profiles

- [X] Allow profiles to be defined, where each profile can be any of
Zed's settings
    - [X] Autocompletion of all settings
    - [X] Errors on invalid keys
- [X] Action brings up modal that shows user-defined profiles
- [X] Alphabetize profiles
- [X] Ability to filter down via keyboard, and navigate via arrow up and
down
- [X] Auto select Disabled option by default (first in list, after
alphabetizing user-defined profiles)
- [X] Automatically select active profile on next picker summoning
- [X] Persist settings until toggled off
- [X] Show live preview as you select from the profile picker
- [X] Tweaking a setting, while in a profile, updates the profile live
- [X] Make sure actions that live update Zed, such as `cmd-0`, `cmd-+`,
and `cmd--`, work while in a profile
- [X] Add a test to track state

Release Notes:

- Added the ability to configure settings profiles, via the "profiles"
key. Example:

```json
{
  "profiles": {
    "Streaming": {
      "agent_font_size": 20,
      "buffer_font_size": 20,
      "theme": "One Light",
      "ui_font_size": 20
    }
  }
}
```

To set a profile, use `settings profile selector: toggle`

Cargo.toml

@@ -119,6 +119,7 @@ members = [
     "crates/paths",
     "crates/picker",
     "crates/prettier",
+    "crates/settings_profile_selector",
     "crates/project",
     "crates/project_panel",
     "crates/project_symbols",
@@ -210,7 +211,7 @@ members = [
     #
 
     "tooling/workspace-hack",
-    "tooling/xtask",
+    "tooling/xtask", "crates/settings_profile_selector",
 ]
 default-members = ["crates/zed"]
 
@@ -342,6 +343,7 @@ picker = { path = "crates/picker" }
 plugin = { path = "crates/plugin" }
 plugin_macros = { path = "crates/plugin_macros" }
 prettier = { path = "crates/prettier" }
+settings_profile_selector = { path = "crates/settings_profile_selector" }
 project = { path = "crates/project" }
 project_panel = { path = "crates/project_panel" }
 project_symbols = { path = "crates/project_symbols" }