feat: introduce experimental diff strategy toggle and enhance diff handling

- Added support for an experimental diff strategy in the Cline class, allowing users to opt for a new unified diff approach.
- Updated the getDiffStrategy function to accommodate the experimental strategy, adjusting the fuzzy match threshold accordingly.
- Integrated experimentalDiffStrategy into the global state management, enabling persistence across sessions.
- Enhanced the ClineProvider and related components to handle the new experimental strategy, including UI updates for user settings.
- Improved task history management to include the experimentalDiffStrategy setting, ensuring consistency in task execution.
- Updated relevant interfaces and types to reflect the new experimentalDiffStrategy property.

src/shared/ExtensionMessage.ts

@@ -70,6 +70,7 @@ export interface ExtensionState {
 	writeDelayMs: number
 	terminalOutputLineLimit?: number
 	mcpEnabled: boolean
+	experimentalDiffStrategy?: boolean
 }
 
 export interface ClineMessage {