refactor: Improve file search tool descriptions and reliability

- Updates the description for the regex_search_files tool to dynamically indicate the regex syntax used based on the user's settings (ECMAScript or Rust).
- Refactors the core plugin match search to wait for the search view to load before attempting to access results, addressing a timing issue.
- Adds new settings for regexSearchBackend and matchSearchBackend in settings.test.ts to reflect the refactored backend options for file searching.

src/types/settings.test.ts

@@ -13,6 +13,8 @@ describe('parseSmartCopilotSettings', () => {
 			openAIApiKey: '',
 			anthropicApiKey: '',
 			filesSearchMethod: 'auto',
+			regexSearchBackend: 'ripgrep',
+			matchSearchBackend: 'coreplugin',
 			fuzzyMatchThreshold: 0.85,
 			geminiApiKey: '',
 			groqApiKey: '',
@@ -196,6 +198,8 @@ describe('settings migration', () => {
 			openAIApiKey: '',
 			anthropicApiKey: '',
 			filesSearchMethod: 'auto',
+			regexSearchBackend: 'ripgrep',
+			matchSearchBackend: 'coreplugin',
 			fuzzyMatchThreshold: 0.85,
 			geminiApiKey: '',
 			groqApiKey: '',