ci: run unit tests on Windows and macOS (#14443)

* ci: run unit tests on Windows and macOS

The Unit Tests CI job only ran on Linux, so platform-specific bugs
invisible to a Linux build could land undetected (e.g. the MSVC-only
NfpPlacer crash fixed in #14267). The full non-[NotWorking] suite already
builds and passes on every shipped arch, so this wires them into CI.

A reusable unit_tests.yml, called once per built arch, downloads that
arch's test artifact and runs ctest. Each build leg builds the test
executables and uploads them; a single publish_test_results job on Linux
aggregates the JUnit results into one check.

Coverage: Linux x86_64 + aarch64, Windows x64 + arm64, macOS arm64.
macOS x86_64 is deferred (cross-built on arm64, needs Rosetta).

- build_release_vs.bat: "tests" token enables BUILD_TESTS
- build_release_macos.sh: -T builds and runs tests; ORCA_TESTS_BUILD_ONLY
  builds them without running (used by CI)
- scripts/run_unit_tests.sh: parameterized test dir and build config

Addresses #11273.

* ci: bump actions/checkout to v7 in reusable unit_tests workflow

Match the actions/checkout v6->v7 bump (#14517) that upstream applied to
the inline test job this reusable workflow replaces.

build_release_macos.sh

@@ -59,7 +59,7 @@ while getopts ":dpa:snt:xbc:i:1Tuh" opt; do
         echo "   -c: Set CMake build configuration, default is Release"
         echo "   -i: Add a prefix to ignore during CMake dependency discovery (repeatable), defaults to /opt/local:/usr/local:/opt/homebrew"
         echo "   -1: Use single job for building"
-        echo "   -T: Build and run tests"
+        echo "   -T: Build and run tests (set ORCA_TESTS_BUILD_ONLY=1 to build without running)"
         exit 0
         ;;
     * )
@@ -209,13 +209,10 @@ function build_slicer() {
             cmake --build . --config "$BUILD_CONFIG" --target "$SLICER_BUILD_TARGET"
         )
 
-        if [ "1." == "$BUILD_TESTS". ]; then
-            echo "Running tests for $_ARCH..."
-            (
-                set -x
-                cd "$PROJECT_BUILD_DIR"
-                ctest --build-config "$BUILD_CONFIG" --output-on-failure
-            )
+        # -T also runs the tests; ORCA_TESTS_BUILD_ONLY=1 builds them without
+        # running, so CI can build here and run them in a dedicated job.
+        if [ "1." == "$BUILD_TESTS". ] && [ "1." != "$ORCA_TESTS_BUILD_ONLY". ]; then
+            "$PROJECT_DIR/scripts/run_unit_tests.sh" "build/$_ARCH/tests" "$BUILD_CONFIG"
         fi
 
         echo "Verify localization with gettext..."