ci: build Windows with build_win.bat and drop the old scripts (#15721)

* ci: build Windows with build_win.bat and drop the old scripts

The deps and slicer jobs called build_release_vs.bat; they now call
build_win.bat. --deps-dir and --build-dir name the build/build-arm64
directories the cache keys and later steps already use, and the
script's own VsDevCmd call replaces the Enter-VsDevShell blocks.
With both stages configured each way into the same directory, the deps
superbuild is byte-identical and the slicer build files are
byte-identical apart from CMakeCache.txt recording how DEP_BUILD_DIR
was set.

Two changes beyond the script swap:

- The compiler is the clang-cl bundled with Visual Studio, the script's
  default. The old script's bare "clang-cl" resolved to the LLVM on the
  runner image's PATH, 20.1.8 on x64 and 22.1.8 on arm64; both arches
  now build with the 22.1.3 VS 18.9 ships. Cached dependencies are only
  rebuilt when deps/ changes, so they stay on the LLVM they were built
  with; the arm64 leg already links deps built with Clang 19 into a
  Clang 22 slicer.
- The deps job no longer zips the dependencies afterwards. The zip was
  never uploaded and was not in the cached path.

A failed cmake --build now fails the job. The old script returned 0, so
the arm64 failure fixed in #15719 was reported as success and the
half-built dependencies were saved to the cache.

build_release.bat, build_release_vs.bat and build_release_vs2022.bat are
removed; nothing referenced them any more.

* ci: run Build all when the Windows build script changes; tests doc builds the deps

The push filter of build_all.yml never listed a build script, and CI
now depends on build_win.bat, so it and its test suite join the list
the pull_request filter already has.

tests/AGENTS.md told Windows to run build_win.bat --run-tests, which
only implies -s and stops at the dependency check on a clean checkout.
The old build_release_vs.bat tests built the dependencies first, so
the line now says -ds --run-tests.

tests/AGENTS.md

@@ -16,7 +16,7 @@ Rules for writing tests under `tests/`. [CATCH2.md](CATCH2.md) is the Catch2 ref
 
 Tests are off by default, so the build has to be told to include them.
 
-- Windows: `build_release_vs.bat tests`, then `ctest --test-dir build/tests -C Release`
+- Windows: `build_win.bat -ds --run-tests`, which builds the dependencies and the tests and runs them (`-l -x` for the clang-cl and Ninja build CI uses)
 - macOS: `./build_release_macos.sh -s -a arm64 -T`, which builds and runs them
 - Linux: `./build_linux.sh -t`, then `ctest --test-dir build/tests -C Release`