Report progress for indexing operations

[radeksimko]

Background

The language server performs indexing of files, which involves parsing, decoding, running external commands or processing HTTP requests to external server - all of which can take time. Currently these time-consuming operations run on the background and don't "block" the user, but until indexing is finished the user may experience inaccurate or incomplete IntelliSense data.

It is currently very difficult/impossible for the user to tell when the indexing has finished.

Indexing happens on the following occasions:

• initialize
• textDocument/didOpen
• textDocument/didChange
• textDocument/didChangeWatchedFiles
• workspace/didChangeWorkspaceFolders

Proposal

• Introduce synchronisation primitives as per Measure performance of indexer(s) #1056
• Report progress on walking and job completion
  • initialize
  • textDocument/didChangeWatchedFiles
  • workspace/didChangeWorkspaceFolders

Implementation Notes

The LSP allows the server to register progress via window/workDoneProgress/* and $/progress.