Migrate keymap and settings + edit predictions rename (#23834)

- [x] snake case keymap properties
- [x] flatten actions
- [x] keymap migration + notfication
- [x] settings migration + notification
- [x] inline completions -> edit predictions 

### future: 
- keymap notification doesn't show up on start up, only on keymap save.
this is existing bug in zed, will be addressed in seperate PR.

Release Notes:

- Added a notification for deprecated settings and keymaps, allowing you
to migrate them with a single click. A backup of your existing keymap
and settings will be created in your home directory.
- Modified some keymap actions and settings for consistency.

---------

Co-authored-by: Piotr Osiewicz <piotr@zed.dev>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/copilot/src/copilot.rs

@@ -17,7 +17,7 @@ use gpui::{
 use http_client::github::get_release_by_tag_name;
 use http_client::HttpClient;
 use language::{
-    language_settings::{all_language_settings, language_settings, InlineCompletionProvider},
+    language_settings::{all_language_settings, language_settings, EditPredictionProvider},
     point_from_lsp, point_to_lsp, Anchor, Bias, Buffer, BufferSnapshot, Language, PointUtf16,
     ToPointUtf16,
 };
@@ -368,8 +368,8 @@ impl Copilot {
         let server_id = self.server_id;
         let http = self.http.clone();
         let node_runtime = self.node_runtime.clone();
-        if all_language_settings(None, cx).inline_completions.provider
-            == InlineCompletionProvider::Copilot
+        if all_language_settings(None, cx).edit_predictions.provider
+            == EditPredictionProvider::Copilot
         {
             if matches!(self.server, CopilotServer::Disabled) {
                 let start_task = cx