Add/default analyzer filter upstream

[pschoffer]

Description of the Change

In order to adjust default analyzer filters, we introduced a WP filter ep_default_analyzer_filters.

For example to enable ascii folding on most fields (e.g. post_title, post_content):

	add_filter( 'ep_default_analyzer_filters', function ( $filters ) {
			return  array( 'ewp_word_delimiter', 'lowercase', 'stop', 'asciifolding', 'ewp_snowball' );
}
		);

Steps to Test

1. Create a post with tittle "Hamburger"
2. Create a post with tittle "Hàmburger"
3. Add the filter from the example above
4. Reindex all the posts using new mappings - vip dev-env exec -- wp vip-search index --setup
5. Search for both Hamburger and Hàmburger should return BOTH posts.

Alternate Designs

Benefits

Possible Drawbacks

Verification Process

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.

Applicable Issues

Changelog Entry

[felipeelia]

Thank you very much for this @pschoffer! Do you mind adding that filter to the other mapping versions as well? Also, can you please add a @since 3.6.2 to their docs? Thanks!

[pschoffer]

Sure, Done @felipeelia .