upgrade to AMBuild 2.2, adopt hl2sdk-manifests for SDK config

Author: pongo1231

.github/workflows/build-on-default-branch-commit.yml

@@ -114,6 +114,11 @@ jobs:
           git clone hl2sdk-proxy-repo -b $sdk hl2sdk-$sdk
         done
 
+    - name: Fetch SDK Manifests
+      shell: bash
+      run: |
+        git clone https://github.com/alliedmodders/hl2sdk-manifests hl2sdk-manifests
+
     - name: Fetch RCBot2
       uses: actions/checkout@v2
       with:

.gitignore

@@ -1,3 +1,7 @@
+# SDK dependencies
+hl2sdk-*/
+hl2sdk-manifests/
+
 # Build outputs
 build/