Reorganize java and add build action for it

.github/workflows/java.yml

@@ -0,0 +1,39 @@
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - java/*
+
+jobs:
+  push:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        tag:
+          - 7
+          - 8
+          - 9
+          - 11
+          - 14
+          - 16
+    steps:
+      - uses: actions/checkout@v2
+      - uses: docker/setup-buildx-action@v1
+        with:
+          version: "v0.5.1"
+          buildkitd-flags: --debug
+      - uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+      - uses: docker/build-push-action@v2
+        with:
+          context: ./java
+          file: ./java/${{ matrix.tag }}/Dockerfile
+          platforms: linux/amd64
+          push: true
+          tags: |
+            ghcr.io/pterodactyl/yolks:java_${{ matrix.tag }}