[CI] Refactor CI actions, use sub-actions, matrices.

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

@@ -0,0 +1,36 @@
+name: Build Godot
+description: Build Godot with the provided options.
+inputs:
+  target:
+    description: The scons target (debug/release_debug/release).
+    default: "debug"
+  tools:
+    description: If tools are to be built.
+    default: false
+  tests:
+    description: If tests are to be built.
+    default: false
+  platform:
+    description: The Godot platform to build.
+    required: false
+  sconsflags:
+    default: ""
+  scons-cache:
+    description: The scons cache path.
+    default: "${{ github.workspace }}/.scons-cache/"
+  scons-cache-limit:
+    description: The scons cache size limit.
+    default: 4096
+runs:
+  using: "composite"
+  steps:
+    - name: Scons Build
+      shell: sh
+      env:
+          SCONSFLAGS: ${{ inputs.sconsflags }}
+          SCONS_CACHE: ${{ inputs.scons-cache }}
+          SCONS_CACHE_LIMIT: ${{ inputs.scons-cache-limit }}
+      run: |
+        echo "Building with flags:" ${{ env.SCONSFLAGS }}
+        scons p=${{ inputs.platform }} target=${{ inputs.target }} tools=${{ inputs.tools }} tests=${{ inputs.tests }} --jobs=2 ${{ env.SCONSFLAGS }}
+        ls -l bin/