[ty] Don't send publish diagnostics for clients supporting pull diagnostics

[MichaReiser]

Summary

fixes: astral-sh/ty#1727

This PR fixes the reported duplicated diagnostic in astral-sh/ty#1727 by skipping publish_diagnostics
if pull diagnostics are enabled, similar to how we do this in other places.

While this PR fixes the duplicate diagnostics, there's still the question why vim sends didChangeWatchedFiles for
a file that's currently open in the editor. The issue with that is that the server is now in this awkward spot
that it has to decide whether it should use the new content on disk OR the content that's currently open in the editor (as reported by didOpen, didChange). For now, ty uses the content sent by didOpen/didChange,
meaning, ty will ignore the new content when checking the project.

I think this is the sensible thing to do here. The client either has to tell the server that the file is now closed,
in which case ty will use the content from disk, or that the user accepted the on-disk changes over the in-editor changes
by sending a didChange notification.

Test Plan

Added E2E test

[astral-sh-bot]

Diagnostic diff on typing conformance tests

No changes detected when running ty on typing conformance tests ✅

[astral-sh-bot]

mypy_primer results

Changes were detected when running on open source projects

scikit-build-core (https://github.com/scikit-build/scikit-build-core)
- src/scikit_build_core/_logging.py:153:13: warning[unsupported-base] Unsupported class base with type `<class 'Mapping[str, Style]'> | <class 'Mapping[str, Divergent]'>`
- Found 42 diagnostics
+ Found 41 diagnostics

No memory usage changes detected ✅

[astral-sh-bot]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[dhruvmanila]

While this PR fixes the duplicate diagnostics, there's still the question why vim sends didChangeWatchedFiles for
a file that's currently open in the editor.

Yeah, I'm not sure either. I looked at the request payload:

{
  jsonrpc = '2.0',
  method = 'workspace/didChangeWatchedFiles',
  params = {
    changes = {
      { type = 3, uri = 'file:///Users/dhruv/dotfiles/4913' },
      { type = 1, uri = 'file:///Users/dhruv/dotfiles/t.py' },
      { type = 3, uri = 'file:///Users/dhruv/dotfiles/t.py~' },
    },
  },
}

It seems to be sending an entry stating that the t.py file was created which seems weird because the file is already open in the editor and it already exists on the filesystem.