Add support for pushing Valkey-Bundle images to GHCR and Amazon ECR

[hanxizh9910]

Addresses #16

Summary

This PR adds support for publishing Valkey Bundle images to Github Container Registry and Amazon ECR Public Gallery

Required Secrets

For ECR publishing to work, the following repository secrets need to be configured:

• AWS_ROLE_TO_ASSUME
• ECR_REPOSITORY_ALIAS
• ECR_REPOSITORY_NAME

Testing

Verified functionality by publishing to personal registries:

• ✅ Docker Hub, GHCR, and ECR publishing working
• ✅ ECR Test Registry: https://gallery.ecr.aws/f2l4i8p5/valkey-bundle
• ✅ GHCR: https://github.com/hanxizh9910/valkey-bundle/pkgs/container/valkey-bundle

[roshkhatri]

Overall good PR, needs a few changes.

[roshkhatri]

LGTM
Asking @Nikhil-Manglore to take a look once

[Nikhil-Manglore]

Code LGTM. In the link pasted above in the description it seems that we're parsing ## in the markdown file. I think it's fine for now because we'll be making that page dynamic anyways so we can update how we parse the template in that PR.

Example:
## What is [Valkey Bundle](https://github.com/valkey-io/valkey-bundle)?

[roshkhatri]

Code LGTM. In the link pasted above in the description it seems that we're parsing ## in the markdown file. I think it's fine for now because we'll be making that page dynamic anyways so we can update how we parse the template in that PR.

Example: ## What is [Valkey Bundle](https://github.com/valkey-io/valkey-bundle)?

Yes we can open an issue for this and track it there.