Search: Add filter to pass other languages to the Jetpack Search Query Parser

[kraftbj]

For situations when we want the ES search to be a different language than the value of get_locale().

Changes proposed in this Pull Request:

• Adds a filter.

Is this a new feature or does it add/remove features to an existing part of Jetpack?

• n/a. In support of JPOP Issue 3536.

Testing instructions:

• Nothing directly to test here, but allows functionality like add_filter( 'jetpack_search_query_languages', function() { return array( 'fr', 'default' ); } );

Proposed changelog entry for your changes:

• Adds filter to adjust Jetpack Search ES query languages.

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello kraftbj! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer, review, and approve D33498-code before merging this PR. Thank you!

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: November 5, 2019.
Scheduled code freeze: October 29, 2019

Generated by 🚫 dangerJS against e6d2b17

[matticbot]

kraftbj, Your synced wpcom patch D33498-code has been updated.

[kraftbj]

I got the itch and PHPCS'd everything.

How the docblock was against the filter was technically correct, but breaking it into a multiline function call makes it overall more readable.