Use file path for detecting package root - #18914

* main:
  [ty] Fix false positives when subscripting an object inferred as having an `Intersection` type (#18920)
  [`flake8-use-pathlib`] Add autofix for `PTH202` (#18763)
  [ty] Add relative import completion tests
  [ty] Clarify what "cursor" means
  [ty] Add a cursor test builder
  [ty] Enforce sort order of completions (#18917)
  [formatter] Fix missing blank lines before decorated classes in .pyi files (#18888)
  Apply fix availability and applicability when adding to `DiagnosticGuard` and remove `NoqaCode::rule` (#18834)
  py-fuzzer: allow relative executable paths (#18915)
  [ty] Change `environment.root` to accept multiple paths (#18913)
  [ty] Rename `src.root` setting to `environment.root` (#18760)
  Use file path for detecting package root (#18914)
  Consider virtual path for various server actions (#18910)
  [ty] Introduce `UnionType::try_from_elements` and `UnionType::try_map` (#18911)
  [ty] Support narrowing on `isinstance()`/`issubclass()` if the second argument is a dynamic, intersection, union or typevar type (#18900)
  [ty] Add decorator check for implicit attribute assignments (#18587)
  [`ruff`] Trigger `RUF037` for empty string and byte strings (#18862)
  [ty] Avoid duplicate diagnostic in unpacking (#18897)
  [`pyupgrade`] Extend version detection to include `sys.version_info.major` (`UP036`) (#18633)
  [`ruff`] Frozen Dataclass default should be valid (`RUF009`) (#18735)