Similar to how we send a `workspace/diagnostic/refresh` request to the client when we get new build settings, we need to send a `workspace/semanticTokens/refresh` to the client to reload semantic tokens when builds settings change. This is particularly important so that we reload semantic tokens from real build setting after a SwiftPM package has finished loading (we previously used fallback settings).
Fixes#2141
rdar://150934682
1bc7d85dbd