Code Editors: remove redundant padding in RTL view

[ramiy]

The new theme/plugin file list has a redundant padding in RTL view.

See the attached screenshots.

plugin-editor-php and theme-editor-php set an inline style on the first level list:
<ul role="group" style="padding-left: 0;">

Inline styles with properties involving left/right values are no good for RTL because the build process for RTL processes just the CSS files, not inline styles in the markup. This CSS declaration should be set in a CSS file, properly targeting the first level <ul>. /cc @WraithKenny

On a side note, WordPress doesn't do the following type of indentation in the PHP files:

	<ul role="tree" aria-labelledby="theme-files-label">
		<li role="treeitem" tabindex="-1" aria-expanded="true"
			aria-level="1"
			aria-posinset="1"
			aria-setsize="1">
			<ul role="group" style="padding-left: 0;">
				<?php wp_print_theme_file_tree( wp_make_theme_file_tree( $allowed_files ) ); ?>
			</ul>
		</li>
	</ul>

This is PHP, not JS, and indenting code this way actually produces a lot of white space in the markup.

The indentation of the element attributes is just for increased readability and maintainability of the PHP code that prints out the HTML. The coding standards have a one-PHP-code-block-per-line sniff. The same was done recently for the Customizer controls. So I don't think necessarily that WordPress doesn't do it, but in contrast I think it often should.

Correction: I realized that this code here isn't outputting attributes via PHP, so they could be on the same line no problem.

In 41865:

File Editor: Move inline to external style to fix extra padding in RTL page direction.

Props afercia.
Fixes #42221.