Extend Sandboxing experiment to Paired AMP modes

[thelovekesh]

Summary

Fixes #7268

Checklist

• My code is tested and passes existing tests.
• My code follows the Engineering Guidelines (updates are often made to the guidelines, check it out periodically).

[westonruter]

For this existing code:

amp-wp/src/MobileRedirection.php

Lines 573 to 583 in 40688e0

	/**
	* Filters the text to be used in the mobile switcher link.
	*
	* Use the `amp_is_request()` function to determine whether you are filtering the
	* text for the link to go to the non-AMP version or the AMP version.
	*
	* @since 2.0
	*
	* @param string $text Link text to display.
	*/
	$text = apply_filters( 'amp_mobile_version_switcher_link_text', $text );

It should probably afterward do:

if ( empty( $text ) ) {
    return;
}

This would allow someone to turn off the link via:

add_filter( 'amp_mobile_version_switcher_styles_used', '__return_false' );
add_filter( 'amp_mobile_version_switcher_link_text', '__return_empty_string' );

[github-actions]

Plugin builds for dbe9350 are ready 🛎️!%0A- Download development build%0A- Download production build

[codecov]

Codecov Report

Merging #7288 (8cc7b58) into develop (650a4eb) will increase coverage by 12.94%.
The diff coverage is 97.87%.

❗ Current head 8cc7b58 differs from pull request most recent head 5e87dbf. Consider uploading reports for the commit 5e87dbf to get more accurate results

@@              Coverage Diff               @@
##             develop    #7288       +/-   ##
==============================================
+ Coverage      64.88%   77.82%   +12.94%     
- Complexity         0     6867     +6867     
==============================================
  Files             67      276      +209     
  Lines           1159    19842    +18683     
==============================================
+ Hits             752    15443    +14691     
- Misses           407     4399     +3992     

Flag	Coverage Δ
javascript	64.88% <ø> (ø)
php	78.63% <97.87%> (?)
unit	78.63% <97.87%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/Sandboxing.php	99.00% <75.00%> (ø)
includes/amp-helper-functions.php	83.05% <100.00%> (ø)
...cludes/validation/class-amp-validation-manager.php	83.20% <100.00%> (ø)
src/MobileRedirection.php	86.29% <100.00%> (ø)
src/Optimizer/Transformer/AmpSchemaOrgMetadata.php	85.71% <0.00%> (ø)
src/Instrumentation/EventWithDuration.php	100.00% <0.00%> (ø)
...ludes/embeds/class-amp-wordpress-embed-handler.php	97.36% <0.00%> (ø)
includes/embeds/class-amp-imgur-embed-handler.php	66.66% <0.00%> (ø)
includes/embeds/class-amp-scribd-embed-handler.php	84.21% <0.00%> (ø)
src/PairedUrlStructure.php	100.00% <0.00%> (ø)
... and 203 more

[westonruter]

I was doing some thorough testing and I found two additional required changes. Almost there!

[westonruter]

Note to self: previously this was done below.

if ( ! amp_is_request() ) {
	add_action( 'wp_head', [ $this, 'add_mobile_alternative_link' ] );
}

[westonruter]

🎉