refactor(vscode): split lsp releated code to linter.ts (#15789)

> This PR refactors the VSCode extension by extracting LSP-related functionality from extension.ts into a new linter.ts module, improving code organization and separation of concerns.
>
> Key Changes:
>
> - Moved LSP client initialization, configuration, and lifecycle management from extension.ts to linter.ts
> -  Created a new commands.ts file to centralize command constants
> -  Simplified extension.ts to focus on extension-level orchestration by delegating to linter-specific functions

Author: Sysix

editors/vscode/client/commands.ts

@@ -0,0 +1,9 @@
+const commandPrefix = 'oxc';
+
+export const enum OxcCommands {
+  RestartServer = `${commandPrefix}.restartServer`,
+  ShowOutputChannel = `${commandPrefix}.showOutputChannel`,
+  ToggleEnable = `${commandPrefix}.toggleEnable`,
+  // only for linter.ts usage
+  ApplyAllFixesFile = `${commandPrefix}.applyAllFixesFile`,
+}