CI: Extract godot-cpp testing into its own job

This ensures that the godot-cpp job has plenty of resources
to run its build and avoid being affected by the main build.

Additionally:
- Extract test tasks into dedicated actions.
- Upload artifacts as early as possible.
- Ensure that we check master cache before random cache.

(cherry picked from commit deb6025781)

.github/actions/download-artifact/action.yml

@@ -0,0 +1,18 @@
+name: Download Godot artifact
+description: Download the Godot artifact.
+inputs:
+  name:
+    description: The artifact name.
+    default: "${{ github.job }}"
+  path:
+    description: The path to download and extract to.
+    required: true
+    default: "./"
+runs:
+  using: "composite"
+  steps:
+    - name: Download Godot Artifact
+      uses: actions/download-artifact@v3
+      with:
+        name: ${{ inputs.name }}
+        path: ${{ inputs.path }}

.github/actions/godot-api-dump/action.yml

@@ -0,0 +1,24 @@
+name: Dump Godot API
+description: Dump Godot API for GDExtension
+inputs:
+  bin:
+    description: The path to the Godot executable
+    required: true
+runs:
+  using: "composite"
+  steps:
+    # Dump GDExtension interface and API
+    - name: Dump GDExtension interface and API for godot-cpp build
+      shell: sh
+      run: |
+        ${{ inputs.bin }} --headless --dump-gdextension-interface --dump-extension-api
+        mkdir godot-api
+        cp -f gdextension_interface.h godot-api/
+        cp -f extension_api.json godot-api/
+
+    - name: Upload API dump
+      uses: ./.github/actions/upload-artifact
+      with:
+        name: 'godot-api-dump'
+        path: './godot-api/*'
+

.github/actions/godot-cache/action.yml

@@ -16,7 +16,20 @@ runs:
       with:
         path: ${{inputs.scons-cache}}
         key: ${{inputs.cache-name}}-${{env.GODOT_BASE_BRANCH}}-${{github.ref}}-${{github.sha}}
+
+        # We try to match an existing cache to restore from it. Each potential key is checked against
+        # all existing caches as a prefix. E.g. 'linux-template-minimal' would match any cache that
+        # starts with "linux-template-minimal", such as "linux-template-minimal-master-refs/heads/master-6588a4a29af1621086feac0117d5d4d37af957fd".
+        #
+        # We check these prefixes in this order:
+        #
+        #   1. The exact match, including the base branch, the commit reference, and the SHA hash of the commit.
+        #   2. A partial match for the same base branch and the same commit reference.
+        #   3. A partial match for the same base branch and the base branch commit reference.
+        #   4. A partial match for the same base branch only (not ideal, matches any PR with the same base branch).
+
         restore-keys: |
           ${{inputs.cache-name}}-${{env.GODOT_BASE_BRANCH}}-${{github.ref}}-${{github.sha}}
           ${{inputs.cache-name}}-${{env.GODOT_BASE_BRANCH}}-${{github.ref}}
+          ${{inputs.cache-name}}-${{env.GODOT_BASE_BRANCH}}-refs/heads/${{env.GODOT_BASE_BRANCH}}
           ${{inputs.cache-name}}-${{env.GODOT_BASE_BRANCH}}

.github/actions/godot-converter-test/action.yml

@@ -0,0 +1,18 @@
+name: Test Godot project converter
+description: Test the Godot project converter.
+inputs:
+  bin:
+    description: The path to the Godot executable
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Test 3-to-4 conversion
+      shell: sh
+      run: |
+        mkdir converter_test
+        cd converter_test
+        touch project.godot
+        ../${{ inputs.bin }} --headless --validate-conversion-3to4
+        cd ..
+        rm converter_test -rf

.github/actions/godot-project-test/action.yml

@@ -0,0 +1,37 @@
+name: Test Godot project
+description: Run the test Godot project.
+inputs:
+  bin:
+    description: The path to the Godot executable
+    required: true
+runs:
+  using: "composite"
+  steps:
+    # Download and extract zip archive with project, folder is renamed to be able to easy change used project
+    - name: Download test project
+      shell: sh
+      run: |
+        wget https://github.com/godotengine/regression-test-project/archive/4.0.zip
+        unzip 4.0.zip
+        mv "regression-test-project-4.0" "test_project"
+
+    # Editor is quite complicated piece of software, so it is easy to introduce bug here.
+
+    - name: Open and close editor (Vulkan)
+      shell: sh
+      run: |
+        xvfb-run ${{ inputs.bin }} --audio-driver Dummy --editor --quit --path test_project 2>&1 | tee sanitizers_log.txt || true
+        misc/scripts/check_ci_log.py sanitizers_log.txt
+
+    - name: Open and close editor (GLES3)
+      shell: sh
+      run: |
+        DRI_PRIME=0 xvfb-run ${{ inputs.bin }} --audio-driver Dummy --rendering-driver opengl3 --editor --quit --path test_project 2>&1 | tee sanitizers_log.txt || true
+        misc/scripts/check_ci_log.py sanitizers_log.txt
+
+    # Run test project
+    - name: Run project
+      shell: sh
+      run: |
+        xvfb-run ${{ inputs.bin }} 40 --audio-driver Dummy --path test_project 2>&1 | tee sanitizers_log.txt || true
+        misc/scripts/check_ci_log.py sanitizers_log.txt