Refactor in preparation to chronos migration (#222)

* Refactor in preparation to chronos migration

Basically extracts 2 files:
- ls with the core langserver functionality
- routes with the actual routes that needs to be handled by the langserver.

* Introduces OnExitCallback so we can remove the pipe dependency in routes

* Removes StreamConnection dependency from ls

* Clean imports in ls and routes so the only removable dep left is the async backend

* Removes faststream deps from suggestapi

* adds fix to refactor