Add github actions

.github/workflows/build.yml

@@ -0,0 +1,47 @@
+name: "Build"
+on:
+  workflow_dispatch: ~
+  push:
+    paths:
+      - "**.java"
+    branches:
+      - "main"
+  pull_request:
+    paths:
+      - "**.java"
+    types:
+      - opened
+      - synchronize
+      - reopened
+jobs:
+  Build-Server-Jar:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Setup Java
+        uses: actions/setup-java@v3
+        with:
+          distribution: temurin
+          java-version: '17'
+      - name: Cache gradle files
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+            ./.gradle/loom-cache
+          key: ${{ runner.os }}-gradle-${{ hashFiles('*.gradle', 'gradle.properties', '**/*.accesswidener') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+      - name: Download latest grasscutter jar
+        run: wget https://nightly.link/Grasscutters/Grasscutter/workflows/build/development/Grasscutter.zip && mkdir lib && unzip Grasscutter.zip -d lib
+        
+      - name: Run Gradle
+        run: ./gradlew jar
+        
+      - name: Upload build
+        uses: actions/upload-artifact@v3
+        with:
+          name: mojoconsole
+          path: opencommand*.jar