feature: Ability to Copy Tags From Another `git_branch` Scope

### Did you check the docs?

- [X] I have read the Grapple docs

### Is your feature request related to a problem? Please describe.

Really enjoy using Grapple! It really improves my workflow so much, so thanks for everything you do maintaining this plugin.

I frequently use the `git_branch` scope, and there are sometimes when I want to copy tags from one scope (`git-branch-a`) to another scope (`git-branch-b`).

Currently, I can do this by yanking all the lines in the popup that comes up with `:Grapple toggle_tags` on `git-branch-a` and pasting them into the popup window when I'm on `git-branch-b`, but it would be nice if there were a less manual way of doing this.

### Describe the solution you'd like

I think it would be nice if there were a command like `:Grapple copy_tags_from ` so it could be used like:

1. `git switch `
2. `nvim -c "Grapple copy_tags_from branch-a"`
3. See the tags from `branch-a` populated into the Grapple scope for `branch-b`

### Describe alternatives you've considered

This process can be done manually by yanking lines displayed when `:Grapple toggle_tags` is called and pasting them into the same popup when on another branch, but it feels like more steps than necessary.

### Additional context

_No response_

Start by tracing the existing :Grapple toggle_tags command and how git_branch scopes store their tags. Define the new :Grapple copy_tags_from entry point, then verify that running it on branch-b populates the tags from branch-a without manual yanking and pasting.

Written by the indexing model from the issue text.