Introduce frontend image build environment tag

To ensure frontend image builds can distinguish between different
environments, an additional distinction based on the environment tag has
been introduced. This change was necessary as the commit altering the
frontend module alone was insufficient. By adding an environment tag to
the image tag name, applications with the same version can now be
uniquely identified across various environments.

Changes Made:
- Modified the Makefile in the govtool/frontend directory to introduce
  an environment tag to the image tag name used in frontend image
  builds. The new tag is generated by appending the environment variable
  to the commit hash obtained from the git log command, ensuring each
  build is uniquely identified per environment.

govtool/frontend/Makefile

@@ -7,7 +7,7 @@ endif
 .DEFAULT_GOAL := push-frontend
 
 # image tags
-frontend_image_tag := $(shell git log -n 1 --format="%H" -- $(root_dir)/govtool/frontend)
+frontend_image_tag := $(shell git log -n 1 --format="%H" -- $(root_dir)/govtool/frontend)-$(env)
 
 .PHONY: build-frontend
 build-frontend: docker-login