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/editor/src/element.rs

@@ -19,7 +19,7 @@ use crate::{
     BlockId, ChunkReplacement, CursorShape, CustomBlockId, DisplayDiffHunk, DisplayPoint,
     DisplayRow, DocumentHighlightRead, DocumentHighlightWrite, EditDisplayMode, Editor, EditorMode,
     EditorSettings, EditorSnapshot, EditorStyle, ExpandExcerpts, FocusedBlock, GoToHunk,
-    GoToPrevHunk, GutterDimensions, HalfPageDown, HalfPageUp, HandleInput, HoveredCursor,
+    GoToPreviousHunk, GutterDimensions, HalfPageDown, HalfPageUp, HandleInput, HoveredCursor,
     InlayHintRefreshReason, InlineCompletion, JumpData, LineDown, LineUp, OpenExcerpts, PageDown,
     PageUp, Point, RowExt, RowRangeExt, SelectPhase, SelectedTextHighlight, Selection, SoftWrap,
     StickyHeaderExcerpt, ToPoint, ToggleFold, COLUMNAR_SELECTION_MODIFIERS, CURSORS_VISIBLE_FOR,
@@ -195,7 +195,7 @@ impl EditorElement {
         register_action(editor, window, Editor::backspace);
         register_action(editor, window, Editor::delete);
         register_action(editor, window, Editor::tab);
-        register_action(editor, window, Editor::tab_prev);
+        register_action(editor, window, Editor::backtab);
         register_action(editor, window, Editor::indent);
         register_action(editor, window, Editor::outdent);
         register_action(editor, window, Editor::autoindent);
@@ -8905,7 +8905,7 @@ fn diff_hunk_controls(
                             move |window, cx| {
                                 Tooltip::for_action_in(
                                     "Previous Hunk",
-                                    &GoToPrevHunk::default(),
+                                    &GoToPreviousHunk::default(),
                                     &focus_handle,
                                     window,
                                     cx,