Social Icon Block missing Movie Services' icons

[janmckell]

What problem does this address?

These services aren't supported by the Social Link block:

• IMDB
• Mubi
• Letterboxd

What is your proposed solution?

Add them, similar to the existing services.

If official SVG icons are hard to find, the w.org/news mockup has copies.
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[jlavoie13]

This seems highly inefficient needing to add support for additional services through the core plugin. This should be extendable for both developers and users.

[kathrynwp]

See also: #39868

[Mamaduka]

Closing in favor of #70261. The extensibility feature will ship in WP 6.9 and is already available in Gutenberg 21.1.

Here's an example plugin - https://github.com/wptrainingteam/devblog-custom-social-icons.