gitlab-ci: init macOS and Windows jobs with per-CMAKE_CONFIGURATION scripts

Apply the approach from commit 747940157f (gitlab-ci: init environment
with per-CMAKE_CONFIGURATION shell scripts, 2021-03-12,
v3.21.0-rc1~480^2~4) to macOS and Windows too.

.gitlab/ci/env.ps1

@@ -0,0 +1,3 @@
+if (Test-Path -Path ".gitlab/ci/env_$env:CMAKE_CONFIGURATION.ps1" -PathType Leaf) {
+  Invoke-Expression ".gitlab/ci/env_$env:CMAKE_CONFIGURATION.ps1"
+}

.gitlab/os-macos.yml

@@ -126,6 +126,7 @@
 ## macOS-specific scripts
 
 .before_script_macos: &before_script_macos
+    - source .gitlab/ci/env.sh
     - .gitlab/ci/cmake.sh
     - export PATH=$PWD/.gitlab/cmake/bin:$PATH
     - .gitlab/ci/ninja.sh

.gitlab/os-windows.yml

@@ -234,6 +234,7 @@
 ## Windows-specific scripts
 
 .before_script_windows: &before_script_windows
+    - Invoke-Expression -Command .gitlab/ci/env.ps1
     - $pwdpath = $pwd.Path
     - powershell -File ".gitlab/ci/wix.ps1"
     - Set-Item -Force -Path "env:WIX" -Value "$pwdpath\.gitlab\wix"
@@ -292,6 +293,7 @@
     stage: test-ext
 
     script:
+        - Invoke-Expression -Command .gitlab/ci/env.ps1
         - build/install/bin/ctest --output-on-failure -V -S .gitlab/ci/ctest_standalone.cmake
 
     interruptible: true