feat(API): Add tag support to public API

[krynble]

Summary

Add tag management functionality to the public API, namely:

• Add tags
• List all existing tags
• Fetch a single tag
• Update a tag
• Delete a tag

As well as:

• Update workflow tags
• Get workflows by tag

Related tickets and issues

https://github.com/n8n-io/n8n/pull/8202 Implemented by @jburgers-chakray - I just updated the PR and fixed a few small things.

Review / Merge checklist

• [ ] PR title and summary are descriptive. Remember, the title automatically goes into the changelog. Use (no-changelog) otherwise. (conventions)
• [ ] Docs updated or follow-up ticket created.
• [ ] Tests included.