editor: Respect search case sensitivity when selecting occurrences (#42121)

Update how the editor's `select_*` methods work in order to respect the
`search.case_sensitive` setting, or to be overriden by the
`BufferSearchBar` search options.

- Update both the `SearchableItem` and `SearchableItemHandle` traits
  with a new `set_search_is_case_sensitive` method that allows callers
  to set the case sensitivity of the search
- Update the `BufferSearchBar` to leverage
  `SearchableItemHandle.set_search_is_case_sensitive` in order to sync
  its case sensitivity options with the searchable item
- Update the implementation of the `SearchableItem` trait for `Editor`
  so as to store the argument provided to the
  `set_search_is_case_sensitive` method
- Update the way search queries are built by `Editor` so as to rely on
  `SearchableItem.set_search_is_case_sensitive` argument, if not `None`,
  or default to the editor's `search.case_sensitive` settings

Closes #41070 

Release Notes:

- Improved the "Select Next Occurrence", "Select Previous Occurrence"
and "Select All Occurrences" actions in order to respect the case
sensitivity search settings

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

docs/src/configuring-zed.md

@@ -3184,13 +3184,53 @@ Non-negative `integer` values
 
 ```json [settings]
 "search": {
+  "button": true,
   "whole_word": false,
   "case_sensitive": false,
   "include_ignored": false,
-  "regex": false
+  "regex": false,
+  "center_on_match": false
 },
 ```
 
+### Button
+
+- Description: Whether to show the project search button in the status bar.
+- Setting: `button`
+- Default: `true`
+
+### Whole Word
+
+- Description: Whether to only match on whole words.
+- Setting: `whole_word`
+- Default: `false`
+
+### Case Sensitive
+
+- Description: Whether to match case sensitively. This setting affects both
+  searches and editor actions like "Select Next Occurrence", "Select Previous
+  Occurrence", and "Select All Occurrences".
+- Setting: `case_sensitive`
+- Default: `false`
+
+### Include Ignore
+
+- Description: Whether to include gitignored files in search results.
+- Setting: `include_ignored`
+- Default: `false`
+
+### Regex
+
+- Description: Whether to interpret the search query as a regular expression.
+- Setting: `regex`
+- Default: `false`
+
+### Center On Match
+
+- Description: Whether to center the cursor on each search match when navigating.
+- Setting: `center_on_match`
+- Default: `false`
+
 ## Search Wrap
 
 - Description: If `search_wrap` is disabled, search result do not wrap around the end of the file