Don't reuse the same diagnostic group id across buffers

This lets us use the group id as the key for an `ElementState`, which
fixes a panic that would occur in project diagnostics when opening it
while there were multiple diagnostic groups with the same id.

Context menu polish

Jump to diagnostic

Now you simply specify a text, an action and a style and GPUI will
take of rendering it properly. This is simpler compared to always
providing a custom element and should make tooltip more consistent
across the UI.

This wraps and derefs to `RenderContext<Editor>`, so that we can
easily use `MouseEventHandler`s in blocks.

Improve server memory usage

We temporarily let it grow when the message size exceed the limit,
but restore the buffer's capacity shortly after. This ensures that,
for each connection in its entire lifetime, we only ever use 1MB.

Introduce context menu to project panel

This can race anyway with snapshot updates, so we just eagerly refresh
the root entry and wait for updates to come in to populate it.

Remove opentelemetry tracing subscriber

We'll see if this stops the server from leaking memory. We still
have spans in our logs.

Co-Authored-By: Antonio Scandurra <me@as-cii.com>

Integration test cleanup

* Use 'build_local_project' helper to reduce boilerplate
* Peform the setup steps in a consistent order

Add a few more important menu items