feat: bundle helm-s3 and helm-git into container images

Resolves #435 (Git as chart repository)
Resolves #220 (S3 as chart repository)
Resolves #436 (About bundling helm plugins)

A lot of thanks to @aslafy-z for authoring the awesome helm-git plugin and contributing it to the community!

Dockerfile

@@ -22,7 +22,9 @@ RUN wget ${HELM_LOCATION}/${HELM_FILENAME} && \
 
 RUN mkdir -p "$(helm home)/plugins"
 RUN helm plugin install https://github.com/databus23/helm-diff && \
-    helm plugin install https://github.com/futuresimple/helm-secrets
+    helm plugin install https://github.com/futuresimple/helm-secrets && \
+    helm plugin install https://github.com/hypnoglow/helm-s3.git && \
+    helm plugin install https://github.com/aslafy-z/helm-git.git
 
 COPY --from=builder /workspace/helmfile/dist/helmfile_linux_amd64 /usr/local/bin/helmfile