workflow: create workflow for generating caches seperately

Google rate limits the pulling so having multiple workflows pulling at
the same time from google seems stupid. Just use github, it was built
for this.

Author: alexytomi

.github/workflows/cache.yml

@@ -0,0 +1,69 @@
+name: Generate Caches
+
+on:
+  workflow_dispatch:
+
+jobs:
+  build:
+# This requires about 25GB to properly download. Please make sure the runner can provide that.
+    runs-on: self-hosted
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+# This bit always takes forever to finish cloning so lets just cache it
+      - name: Cache third_party/llvm
+        uses: actions/cache@v4
+        with:
+          path: third_party/llvm
+          key: ${{ matrix.os }}-third_party-llvm
+      - name: Cache third_party/VK-GL-CTS
+        uses: actions/cache@v4
+        with:
+          path: third_party/VK-GL-CTS
+          key: ${{ matrix.os }}-third_party-VK-GL-CTS
+      - name: Cache third_party/SwiftShader
+        uses: actions/cache@v4
+        with:
+          path: third_party/SwiftShader
+          key: ${{ matrix.os }}-third_party-SwiftShader
+      - name: Cache third_party/dawn
+        uses: actions/cache@v4
+        with:
+          path: third_party/dawn
+          key: ${{ matrix.os }}-third_party-dawn
+      - name: Cache depot_tools
+        uses: actions/cache@v4
+        with:
+          path: depot_tools
+          key: ${{ runner.os }}-depot-tools
+# This should only be rarely ran so its here so the cache priority still is somewhat biggest to smallest
+      - name: Install depot_tools
+        run: |
+          if [ ! -d "depot_tools" ] ; then
+          git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
+          fi
+          echo "$PWD/depot_tools" >> $GITHUB_PATH
+      - name: Cache tools
+        uses: actions/cache@v4
+        with:
+          path: tools
+          key: ${{ matrix.os }}-tools
+      - name: Cache build
+        uses: actions/cache@v4
+        with:
+          path: build
+          key: ${{ matrix.os }}-build
+
+      - name: Fetch ANGLE and dependencies
+        run: |
+          gclient config --spec 'solutions = [
+            {
+              "name": ".",
+              "url": "https://chromium.googlesource.com/angle/angle.git",
+              "deps_file": "DEPS",
+              "managed": False,
+              "custom_vars": {},
+            },
+          ]
+          target_os = ["ios", "android"]'
+          gclient sync -Rf