Add new filter ep_default_analyzer_char_filters

[rebeccahum]

Description of the Change

html_strip doesn't allow searching for text within HTML comments. So, with Gutenberg blocks, if one wanted to search for the Jetpack Slideshow block with jetpack/slideshow, it can't be done.

It would be nice if users had that option to filter it out.

Alternate Designs

N/A.

Possible Drawbacks

N/A.

Verification Process

1. Add a Jetpack slideshow block to a post
2. Add the filter to disable the html_strip:

add_filter( 'ep_default_analyzer_char_filter', '__return_empty_array' );

3. Re-index with mappings re-put in place
4. Search for "slideshow" and see result

Checklist:

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

Changelog Entry

Added: New filter ep_default_analyzer_char_filters

Credits

Props @rebeccahum