Optimizations to path resolving

[JonatanWaern]

• Cache path resolver, invalidating as necessary
• Cache file resolver calls

[Copilot]

Pull Request Overview

This PR optimizes path resolution performance by implementing caching mechanisms at two levels: caching the path resolver itself and caching individual file resolution calls. This should significantly improve server startup time, particularly for complex include trees.

• Caches the PathResolver instance to avoid repeated reconstruction
• Adds caching for individual path resolution results using a RefCell-wrapped HashMap
• Updates workspace management to invalidate the cached resolver when workspaces change

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/server/mod.rs	Updates initialization to pass output parameter for workspace updates
src/file_management.rs	Adds path resolution result caching with RefCell HashMap and cache lookup wrapper
src/actions/notifications.rs	Updates workspace folder change handler to pass output parameter
src/actions/mod.rs	Implements PathResolver caching with invalidation on workspace changes
CHANGELOG.md	Documents the performance improvement for path resolution

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