Incorrect XML namespace on Block Editor icons UI

[wp-seopress]

Description

Some of the SVG icons used in the block editor UI use an incorrect XML namespace:

https://www.w3.org/2000/svg

I count 6 icons with this issue.

We should replace https to http as stated in the official documentation here: https://www.w3.org/2000/svg

This solves the problem of reusing these SVG icons with other apps/sites...

Step-by-step reproduction instructions

1. Open the Editor
2. Go to the Style Guide, Blocks, and inspect the Custom Link SVG icon with your browser

Screenshots, screen recording, code snippet

Environment info

• Brand new WP 6.3 installation, default themes, no plugin

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes