Feature/filter enable x frame options

Description of the Change

According to Mozilla, X-Frame-Options only has 2 valid values:

SAMEORIGIN - Only allow an iframe to be used on the same domain
DENY - Do not allow any embedded iframe

The existing filter only allows for this to be changed from (default) SAMEORIGIN to DENY

Benefits

There is an option to filter wp_headers to remove this header, if present; this additional filter allows setting the header to be bypassed entirely.

Possible Drawbacks

None

Verification Process

add_filter( 'tenup_experience_disable_x_frame_options', true ) - result is the header is not set.

Checklist:

[ ] I have read the CONTRIBUTING document. No, the file doesn't exist in this repo
[x] My code follows the code style of this project.
[ ] My change requires a change to the documentation. Maybe
[x] I have updated the documentation accordingly.
[ ] I have added tests to cover my change. There are no existing tests; should these be added?
[ ] All new and existing tests passed.

Changelog Entry

Added: filter tenup_experience_disable_x_frame_options to allow omission of the X-Frame-Options header.

10up / 10up-experience