keymap: Update Prev to Previous for consistency (#25909)

Closes #10167

This is take 2 on https://github.com/zed-industries/zed/pull/2341 which
was closed due to lack of migrator.

This PR contains rename of following keymap actions: 
```sh
1. ["editor::GoToPrevHunk", { "center_cursor": true }] -> ["editor::GoToPreviousHunk", { "center_cursor": true }]
2. "editor::GoToPrevDiagnostic" -> "editor::GoToPreviousDiagnostic"
3. "editor::ContextMenuPrev" -> "editor::ContextMenuPrevious"
4. "search::SelectPrevMatch" -> "search::SelectPreviousMatch"
5. "file_finder::SelectPrev" -> "file_finder::SelectPrevious"
6. "menu::SelectPrev" -> "menu::SelectPrevious"
7. "editor::TabPrev" -> "editor::Backtab"
```

Release Notes:

- Renamed several keymap actions for consistency (e.g., `GoToPrevHunk` →
`GoToPreviousHunk`, `TabPrev` → `Backtab`). Your existing configured
keybindings will still work. You can click **"Backup and Update"** at
the top of your keymap file to easily update to the new actions.


Co-authored-by: Joseph T. Lyons <JosephTLyons@gmail.com>

crates/zeta/src/rate_completion_modal.rs

@@ -82,7 +82,12 @@ impl RateCompletionModal {
         cx.notify();
     }
 
-    fn select_prev(&mut self, _: &menu::SelectPrev, _: &mut Window, cx: &mut Context<Self>) {
+    fn select_previous(
+        &mut self,
+        _: &menu::SelectPrevious,
+        _: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
         self.selected_index = self.selected_index.saturating_sub(1);
         cx.notify();
     }
@@ -529,7 +534,7 @@ impl Render for RateCompletionModal {
             .track_focus(&self.focus_handle)
             .on_action(cx.listener(Self::dismiss))
             .on_action(cx.listener(Self::confirm))
-            .on_action(cx.listener(Self::select_prev))
+            .on_action(cx.listener(Self::select_previous))
             .on_action(cx.listener(Self::select_prev_edit))
             .on_action(cx.listener(Self::select_next))
             .on_action(cx.listener(Self::select_next_edit))