Define GitHub Actions workflow for Core module

This is an initial implementation of the CI process to check formatting,
build contracts, test them and run deployment with local hardhat
network.

.github/workflows/core.yaml

@@ -0,0 +1,106 @@
+name: Core
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "core/**"
+  pull_request:
+
+defaults:
+  run:
+    working-directory: ./core
+
+jobs:
+  core-format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Node
+        uses: actions/setup-node@v3
+        with:
+          node-version-file: "core/.nvmrc"
+          cache: "yarn"
+          cache-dependency-path: "core/yarn.lock"
+
+      - name: Install Dependencies
+        run: yarn install --prefer-offline --frozen-lockfile
+
+      - name: Format
+        run: yarn format
+
+  core-build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Node
+        uses: actions/setup-node@v3
+        with:
+          node-version-file: "core/.nvmrc"
+          cache: "yarn"
+          cache-dependency-path: "core/yarn.lock"
+
+      - name: Install Dependencies
+        run: yarn install --prefer-offline --frozen-lockfile
+
+      - name: Build
+        run: yarn build
+
+      - name: Upload Build Artifacts
+        uses: actions/upload-artifact@v3
+        with:
+          name: core-build
+          path: core/build/
+
+  core-test:
+    needs: [core-build]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Node
+        uses: actions/setup-node@v3
+        with:
+          node-version-file: "core/.nvmrc"
+          cache: "yarn"
+          cache-dependency-path: "core/yarn.lock"
+
+      - name: Install Dependencies
+        run: yarn install --prefer-offline --frozen-lockfile
+
+      - name: Download Build Artifacts
+        uses: actions/download-artifact@v3
+        with:
+          name: core-build
+          path: core/build/
+
+      - name: Test
+        run: yarn test
+
+  core-deploy-dry-run:
+    needs: [core-build]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Node
+        uses: actions/setup-node@v3
+        with:
+          node-version-file: "core/.nvmrc"
+          cache: "yarn"
+          cache-dependency-path: "core/yarn.lock"
+
+      - name: Install Dependencies
+        run: yarn install --prefer-offline --frozen-lockfile
+
+      - name: Download Build Artifacts
+        uses: actions/download-artifact@v3
+        with:
+          name: core-build
+          path: core/build/
+
+      - name: Deploy
+        run: yarn deploy