Add VS 2019-2022 C+14/17 jobs to GHA

For now I added only the basic build matrix, without coverage
collection and more special builds, like WMAIN.

However, due to GHA being so much faster than AppVeyor, all
these builds are now done against the 'all-tests' prefix, making
the builds more uniform than they were on AppVeyor.

.github/workflows/windows-simple-builds.yml

@@ -0,0 +1,39 @@
+name: Windows builds (basic)
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: ${{matrix.os}}, ${{matrix.std}}, ${{matrix.build_type}}
+    runs-on: ${{matrix.os}}
+    strategy:
+      matrix:
+        os: [windows-2019, windows-2022]
+        platform: [Win32, x64]
+        build_type: [Debug, Release]
+        std: [14, 17]
+    steps:
+      - uses: actions/checkout@v2
+      
+      - name: Configure build
+        working-directory: ${{runner.workspace}}
+        run: |
+          cmake -S $Env:GITHUB_WORKSPACE               `
+                -B ${{runner.workspace}}/build         `
+                -DCMAKE_CXX_STANDARD=${{matrix.std}}   `
+                -A ${{matrix.platform}}                `
+                --preset all-tests
+      
+      - name: Build tests
+        working-directory: ${{runner.workspace}}
+        run: |
+          $jobs = (Get-CimInstance Win32_ComputerSystem).NumberOfLogicalProcessors
+          cmake --build build --config ${{matrix.build_type}} --parallel $jobs
+      
+      - name: Run tests
+        working-directory: ${{runner.workspace}}/build
+        env:
+            CTEST_OUTPUT_ON_FAILURE: 1
+        run: |
+          $jobs = (Get-CimInstance Win32_ComputerSystem).NumberOfLogicalProcessors
+          ctest -C ${{matrix.build_type}} -j $jobs