gitlab-ci: add pre-build and post-build steps to Windows

Apply the approach from commit 372ce5bffe (ci: add pre-build and
post-build steps to Linux, 2022-12-05, v3.26.0-rc1~225^2~1) to
build jobs on Windows.

.gitlab/ci/post_build.ps1

@@ -0,0 +1,4 @@
+$pwsh = [System.Diagnostics.Process]::GetCurrentProcess().MainModule.FileName
+if (Test-Path -Path ".gitlab/ci/post_build_$env:CMAKE_CONFIGURATION.ps1" -PathType Leaf) {
+  . ".gitlab/ci/post_build_$env:CMAKE_CONFIGURATION.ps1"
+}

.gitlab/ci/pre_build.ps1

@@ -0,0 +1,4 @@
+$pwsh = [System.Diagnostics.Process]::GetCurrentProcess().MainModule.FileName
+if (Test-Path -Path ".gitlab/ci/pre_build_$env:CMAKE_CONFIGURATION.ps1" -PathType Leaf) {
+  . ".gitlab/ci/pre_build_$env:CMAKE_CONFIGURATION.ps1"
+}

.gitlab/os-windows.yml

@@ -358,8 +358,10 @@
         - Invoke-Expression -Command .gitlab/ci/vcvarsall.ps1
         - sccache --start-server
         - sccache --show-stats
+        - (& "$pwsh" -File ".gitlab/ci/pre_build.ps1")
         - ctest -VV -S .gitlab/ci/ctest_configure.cmake
         - ctest -VV -S .gitlab/ci/ctest_build.cmake
+        - (& "$pwsh" -File ".gitlab/ci/post_build.ps1")
         - sccache --show-stats
         - sccache --stop-server