Add clojure-lsp startup progress in status bar

[bpringe]

The support was recently added to clojure-lsp using the protocol. Clojure-lsp will send messages reporting its progress like "5% resolving source-paths" and I think we just need to relay this info to the status bar.

[bpringe]

A link to the relevant protocol info: https://microsoft.github.io/language-server-protocol/specification#progress