Closes #ISSUE
Adds a new `documentation` method to actions, that is extracted from doc
comments when using the `actions!` or derive macros.
Additionally, this PR adds doc comments to as many action definitions in
Zed as possible.
Release Notes:
- N/A *or* Added/Fixed/Improved ...
Closes#10454
Implements SVG file preview capability similar to the existing markdown
preview.
- Adds `svg_preview` crate with preview view and live reloading upon
file save.
- Integrates SVG preview button in quick action bar.
- File preview shortcuts (`ctrl/cmd+k v` and `ctrl/cmd+shift+v`) are
extension-aware.
Release Notes:
- Added SVG file preview, accessible via the quick action bar button or
keyboard shortcuts (`ctrl/cmd+k v` and `ctrl/cmd+shift+v`) when editing
SVG files.
