Enable configuring edit prediction providers through the settings UI (#44505)

- Edit prediction providers can now be configured through the settings
UI
- Cleaned up the status bar menu to only show _configured_ providers
- Added to the status bar icon button tooltip the name of the active
provider
- Only display the data collection functionality under "Privacy" for the
Zed models
- Moved the Codestral edit prediction provider out of the Mistral
section in the agent panel into the settings UI
- Refined and improved UI and states for configuring GitHub Copilot as
both an agent and edit prediction provider

#### Todos before merge:

- [x] UI: Unify with settings UI style and tidy it all up
- [x] Unify Copilot modal `impl`s to use separate window
- [x] Remove stop light icons from GitHub modal
- [x] Make dismiss events work on GitHub modal
- [ ] Investigate workarounds to tell if Copilot authenticated even when
LSP not running


Release Notes:

- settings_ui: Added a section for configuring edit prediction providers
under AI > Edit Predictions, including Codestral and GitHub Copilot.
Once you've updated you can use the following link to open it:
zed://settings/edit_predictions.providers

---------

Co-authored-by: Ben Kunkle <ben@zed.dev>

Cargo.lock

@@ -5111,7 +5111,6 @@ dependencies = [
  "cloud_llm_client",
  "collections",
  "copilot",
- "credentials_provider",
  "ctor",
  "db",
  "edit_prediction_context",
@@ -5275,7 +5274,6 @@ dependencies = [
  "text",
  "theme",
  "ui",
- "ui_input",
  "util",
  "workspace",
  "zed_actions",
@@ -8802,6 +8800,7 @@ dependencies = [
  "cloud_api_types",
  "cloud_llm_client",
  "collections",
+ "credentials_provider",
  "futures 0.3.31",
  "gpui",
  "http_client",
@@ -8820,6 +8819,7 @@ dependencies = [
  "telemetry_events",
  "thiserror 2.0.17",
  "util",
+ "zed_env_vars",
 ]
 
 [[package]]
@@ -8876,7 +8876,6 @@ dependencies = [
  "util",
  "vercel",
  "x_ai",
- "zed_env_vars",
 ]
 
 [[package]]
@@ -14778,6 +14777,8 @@ dependencies = [
  "assets",
  "bm25",
  "client",
+ "copilot",
+ "edit_prediction",
  "editor",
  "feature_flags",
  "fs",
@@ -14786,6 +14787,7 @@ dependencies = [
  "gpui",
  "heck 0.5.0",
  "language",
+ "language_models",
  "log",
  "menu",
  "node_runtime",