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/vim/src/test.rs

@@ -17,12 +17,7 @@ use indoc::indoc;
 use search::BufferSearchBar;
 use workspace::WorkspaceSettings;
 
-use crate::{
-    insert::NormalBefore,
-    motion,
-    state::{Mode, Operator},
-    PushOperator,
-};
+use crate::{insert::NormalBefore, motion, state::Mode, PushSneak, PushSneakBackward};
 
 #[gpui::test]
 async fn test_initially_disabled(cx: &mut gpui::TestAppContext) {
@@ -1347,17 +1342,17 @@ async fn test_sneak(cx: &mut gpui::TestAppContext) {
         cx.bind_keys([
             KeyBinding::new(
                 "s",
-                PushOperator(Operator::Sneak { first_char: None }),
+                PushSneak { first_char: None },
                 Some("vim_mode == normal"),
             ),
             KeyBinding::new(
                 "S",
-                PushOperator(Operator::SneakBackward { first_char: None }),
+                PushSneakBackward { first_char: None },
                 Some("vim_mode == normal"),
             ),
             KeyBinding::new(
                 "S",
-                PushOperator(Operator::SneakBackward { first_char: None }),
+                PushSneakBackward { first_char: None },
                 Some("vim_mode == visual"),
             ),
         ])