feat(ci): move rust docker target bash to shell script

.github/workflows/rust.yml

@@ -12,8 +12,8 @@ on:
     - 'services/gateway/**'
     - 'services/avatars/**'
     - '.github/workflows/rust.yml'
-    - 'Dockerfile.rust'
-    - 'Dockerfile.bin'
+    - 'ci/Dockerfile.rust'
+    - 'ci/rust-docker-target.sh'
     - 'Cargo.toml'
     - 'Cargo.lock'
 
@@ -40,7 +40,7 @@ jobs:
         with:
           # https://github.com/docker/build-push-action/issues/378
           context: .
-          file: Dockerfile.rust
+          file: ci/Dockerfile.rust
           push: false 
           cache-from: type=registry,ref=ghcr.io/pluralkit/docker-cache:rust
           cache-to: type=registry,ref=ghcr.io/pluralkit/docker-cache:rust,mode=max
@@ -48,13 +48,7 @@ jobs:
 
       # add more binaries here
       - run: |
-          for binary in "api" "gateway" "avatars"; do
-            for tag in latest ${{ env.BRANCH_NAME }} ${{ github.sha }}; do
-              cat Dockerfile.bin | sed "s/__BINARY__/$binary/g" | docker build -t ghcr.io/pluralkit/$binary:$tag -f - .
-            done
-            if [ "${{ github.repository }}" == "PluralKit/PluralKit" ]; then
-              docker push ghcr.io/pluralkit/$binary:${{ env.BRANCH_NAME }}
-              docker push ghcr.io/pluralkit/$binary:${{ github.sha }}
-              [ "${{ env.BRANCH_NAME }}" == "main" ] && docker push ghcr.io/pluralkit/$binary:latest
-            fi
-          done
+          tag=${{ github.sha }} \
+          branch=${{ env.BRANCH_NAME }} \
+          push=$([ "${{ github.repository }}" == "PluralKit/PluralKit" ] && echo true || echo false) \
+          ci/rust-docker-target.sh