Fix/replace svn with git sparse checkout

[weijing24]

GitHub sunset SVN support in January 2024, breaking the svn ice used to download subdirectories (e.g., OMZ plugins). This replaces the SVN implementation with git sparse-checkout which provides the same subdirectory cloning capability using native git.

Changes:

• ZI_1MAP: remove /trunk/ from URLs (no longer needed for git)
• .zi-mirror-using-svn(): rewrite to use git clone --no-checkout --depth=1 --filter=tree:0 + git sparse-checkout
• side.zsh: detect .git in addition to .svn for existing snippets
• autoload.zsh: use git status when .git dir is present

Description

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update (if none of the other choices apply)
• Chore (general maintenance, refactoring, or code style update)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have updated the documentation accordingly.

Other information (if applicable)

[weijing24]

Can anybody check this pr ?

[github-actions]

There hasn't been any activity on this pull request recently, and in order to prioritize active work, it has been marked as stale.
This PR will be closed and locked in 7 days if no further activity occurs.
Thank you for your contributions!

[github-actions]

Pull Request closed and locked due to lack of activity.
If you'd like to build on this closed PR, you can clone it using this method: https://stackoverflow.com/a/14969986
Then open a new PR, referencing this closed PR in your message.

[ss-o]

This PR has been open since March 11 without updates. The SVN removal work has been addressed differently in the main branch (via z-a-meta-plugins).

Could you rebase this on next and resolve the conflicts? If the SVN→sparse-checkout approach is still the intended direction for zi core, we'd be happy to review an updated version. Otherwise we may close this in ~2 weeks.