Introduce strip_dynamic_blocks() for excerpts

[obenland]

Description

Aims to fix #7268 by adding parity with strip_shortcodes() in wp_trim_excerpt().
Aims to fix #5572 by removing dynamic blocks when generating excerpts to avoid infinite loops when dynamic blocks generate excerpts themselves.

How has this been tested?

I created a dynamic block that generated an excerpt in its callback, embedded it, and tested that it didn't create an out-of-memory error. Also added a small unit test to verify dynamic blocks are stripped.

Types of changes

• Moves generating dynamic block regex into its own function, similar to get_shortcode_regex().
• Introduces strip_dynamic_blocks() function.
• Introduces a unit test for strip_dynamic_blocks().
• Calls strip_dynamic_blocks() when generating an excerpt.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.

[pento]

This approach works for me: dynamic blocks are functionally equivalent to shortcodes for this use case, it's quite reasonable to just strip them out. Nice work on the hack to get around the lack of convenient filter. 😉

The docblocks need to be filled out, but the implementation is otherwise good. Feel free to merge once you've updated them. 🙂

[maximebj]

Very nice! Thank you very much!