Implement basic settings for View Transitions plugin

[felixarntz]

Summary

See #1997: This adds basic settings to control the theme support arguments for the View Transitions plugin.

Relevant technical choices

• Adds settings UI under Settings > Reading for View Transitions theme support arguments:
  • Animation for the default transition type.
  • Selectors for the default configured view transition names.
• Each setting is optional and merely for customization. The controls allow modifying what would otherwise require to change code, via add_theme_support( 'view-transitions', $args ).
• The settings are applied to the theme support arguments, overriding / merged into whatever is configured via code.
• A "Settings" link pointing to the relevant UI is shown in the plugins list table.
• Minor tweak: The ! defined( 'ABSPATH' ) check was added to all plugin files where it was missing.

Note: Most of the code is inspired by the relatively similar settings implementation for the Speculative Loading plugin. In fact, I copied that code over as a starting point.

Settings UI Screenshot

[github-actions]

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Co-authored-by: felixarntz <[email protected]>
Co-authored-by: westonruter <[email protected]>
Co-authored-by: mukeshpanchal27 <[email protected]>
Co-authored-by: swissspidy <[email protected]>

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[codecov]

Codecov Report

Attention: Patch coverage is 0.44643% with 223 lines in your changes missing coverage. Please review.

Project coverage is 68.05%. Comparing base (79fd9c0) to head (95d0b4d).
Report is 16 commits behind head on trunk.

Files with missing lines	Patch %	Lines
plugins/view-transitions/includes/settings.php	0.00%	203 Missing ⚠️
plugins/view-transitions/uninstall.php	0.00%	16 Missing ⚠️
plugins/view-transitions/hooks.php	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #2025      +/-   ##
==========================================
- Coverage   70.01%   68.05%   -1.96%     
==========================================
  Files          91       92       +1     
  Lines        7603     7622      +19     
==========================================
- Hits         5323     5187     -136     
- Misses       2280     2435     +155     

Flag	Coverage Δ
multisite	68.05% <0.44%> (-1.96%)	⬇️
single	36.99% <0.00%> (-2.61%)	⬇️

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[westonruter]

There's also no guarantee that $args['field'] is defined. If not set, perhaps this should short-circuit if the expected array keys aren't defined?

Suggested change

	switch ( $args['field'] ) {
	if ( ! isset( $args['field'], $args['label_for'], $args['field'], $args['description'] ) ) {
	return;
	}
	switch ( $args['field'] ) {

Granted, this is highly unlikely.

[felixarntz]

There's no guarantee from a PHP perspective, but isn't it required at least from a PHPStan perspective due to how the @param is defined? Also it's worth noting this is a private function, so that plus the PHPStan annotation might make this unnecessary.

On the other hand, of course it's good for defensive coding. In that case though, I think we should only bail for field and label_for missing, since description is optional in the first place - if it's not set, we should just not render a description.

[westonruter]

LGTM