test(e2e): cache firestore emulator

Author: mikehardy

.github/workflows/tests_e2e.yml

@@ -50,6 +50,12 @@ jobs:
           max_attempts: 3
           command: npm i -g firebase-tools
 
+      - name: Cache Firestore Emulator
+        uses: actions/cache@v2
+        with:
+          path: ~/.cache/firebase/emulators
+          key: firebase-emulators-v1
+
       - name: Start Firestore Emulator
         run: yarn tests:emulator:start-ci
 
@@ -229,6 +235,12 @@ jobs:
           max_attempts: 3
           command: npm i -g firebase-tools
 
+      - name: Cache Firestore Emulator
+        uses: actions/cache@v2
+        with:
+          path: ~/.cache/firebase/emulators
+          key: firebase-emulators-v1
+
       - name: Start Firestore Emulator
         run: yarn tests:emulator:start-ci