[ci]: add testing pipelines to github actions (#1159)

move pipeline testing from AzDO to GitHub Actions.

* update clang versions to 13-15
* update gcc versions to 10-12
* update xcode versions to 14.3.1 and 15.4
* test against C++23 (where supported)

.github/workflows/cmake/action.yml

@@ -0,0 +1,56 @@
+name: Composite CMake
+inputs:
+  cmake_generator:
+    required: false
+    type: string
+    default: 'Unix Makefiles'
+  cmake_build_type:
+    required: true
+    type: string
+    default: ''
+  cmake_cxx_compiler:
+    required: false 
+    type: string 
+  gsl_cxx_standard:
+    required: true
+    type: number
+  extra_cmake_args:
+    required: false
+    type: string
+    default: ''
+  build_cmd:
+    required: true 
+    type: string 
+    default: 'make'
+  test_cmd:
+    required: false
+    type: string 
+    default: 'make test'
+  shell:
+    required: false 
+    type: string
+    default: 'bash'
+
+
+runs:
+  using: composite
+  steps:
+    - name: Create build directory
+      run: mkdir build
+      shell: ${{ inputs.shell }}
+
+    - name: Configure CMake
+      working-directory: build
+      run: cmake -G "${{ inputs.cmake_generator }}" -DCMAKE_BUILD_TYPE=${{ inputs.cmake_build_type }} -DCMAKE_CXX_COMPILER=${{ inputs.cmake_cxx_compiler }} -DGSL_CXX_STANDARD=${{ inputs.gsl_cxx_standard }} -DCI_TESTING:BOOL=ON -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON -Werror=dev ${{ inputs.extra_cmake_args }} ..
+      shell: ${{ inputs.shell }}
+
+    - name: Build
+      working-directory: build
+      run: ${{ inputs.build_cmd }}
+      shell: ${{ inputs.shell }}
+
+    - name: Test
+      working-directory: build
+      run: ${{ inputs.test_cmd }}
+      shell: ${{ inputs.shell }} 
+

.github/workflows/compilers.yml

@@ -0,0 +1,104 @@
+name: Compiler Integration Tests
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+# These jobs are correlated with the officially supported compilers
+# and toolsets. If you change any versions, please update README.md.
+
+jobs:
+  gcc:
+    strategy:
+      matrix:
+        gcc_version: [ 10, 11, 12 ]
+        build_type: [ Debug, Release ]
+        cxx_version: [ 14, 17, 20, 23 ]
+        exclude:
+          - gcc_version: 10
+            cxx_version: 23
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run CMake (configure, build, test)
+        uses: ./.github/workflows/cmake
+        with:
+          cmake_build_type: ${{ matrix.build_type }}
+          cmake_cxx_compiler: g++-${{ matrix.gcc_version }}
+          gsl_cxx_standard: ${{ matrix.cxx_version }}
+          
+  clang:
+    strategy:
+      matrix:
+        clang_version: [ 13, 14, 15 ]
+        build_type: [ Debug, Release ]
+        cxx_version: [ 14, 17, 20, 23 ]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+     
+      - name: Run CMake (configure, build, test)
+        uses: ./.github/workflows/cmake
+        with:
+          cmake_build_type: ${{ matrix.build_type }}
+          cmake_cxx_compiler: clang++-${{ matrix.clang_version }}
+          gsl_cxx_standard: ${{ matrix.cxx_version }}
+
+  xcode:
+    strategy:
+      matrix:
+        xcode_version: [ '14.3.1', '15.4' ]
+        build_type: [ Debug, Release ]
+        cxx_version: [ 14, 17, 20, 23 ]
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: select xcode version
+        run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode_version }}.app
+
+      - name: Run CMake (configure, build, test)
+        uses: ./.github/workflows/cmake
+        with:
+          cmake_build_type: ${{ matrix.build_type }}
+          cmake_cxx_compiler: clang++
+          gsl_cxx_standard: ${{ matrix.cxx_version }}
+
+  VisualStudio:
+    strategy:
+      matrix:
+        generator: [ 'Visual Studio 16 2019', 'Visual Studio 17 2022' ]
+        image: [ windows-2019, windows-2022 ]
+        build_type: [ Debug, Release ]
+        extra_args: [ '', '-T ClangCL' ]
+        cxx_version: [ 14, 17, 20, 23 ]
+        exclude:
+          - generator: 'Visual Studio 17 2022'
+            image: windows-2019
+          - generator: 'Visual Studio 16 2019'
+            image: windows-2022
+          - generator: 'Visual Studio 16 2019'
+            cxx_version: 23
+    runs-on: ${{ matrix.image }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: microsoft/setup-msbuild@v2
+
+      - name: Run CMake (configure, build, test)
+        uses: ./.github/workflows/cmake
+        with:
+          cmake_generator: ${{ matrix.generator }}
+          cmake_build_type: ${{ matrix.build_type }}
+          gsl_cxx_standard: ${{ matrix.cxx_version }}
+          extra_cmake_args: ${{ matrix.extra_args }}
+          build_cmd: msbuild GSL.sln
+          test_cmd: ctest . --output-on-failure --no-compress-output
+          shell: pwsh
+