ci: Update docker-build-push workflow actions

[RobertGemmaJr]

Confirmed that the images are being built and added to GHCR. We'll have to change the required status checks since the name of the action as changed in this PR.

• Manages the IMAGE_NAME variable via the repository instead of hard-coding it
• Adda a concurrency to ensure PR builds are cancelled when there are new commits
• Updates the actions to their latest versions
• Removes the docker/setup-qemu-action
  • This is only needed if we're building for multiple CPU architectures
• Adds the platforms field to the docker/build-and-push-action
  • Guarantees we build the image for the correct CPU architecture
• Adds action caching to the docker/build-and-push-action