Prevent CSS from loading on unrelated pages

[iandunn]

Fixes #35

The check for bbp_get_displayed_user_id() isn't perfect, since it'll still load the stylesheet on a handful of pages that don't display the block. I think it's good enough for a quick workaround, though. Hopefully we can move to viewStyle in the future and remove this code.

To test, look for the wporg-two-factor-settings-style-css stylesheet ID in response source, or the wp-content/plugins/wporg-two-factor/settings/build/style-index.css URL in the Network tab of browser dev tools.

> curl -is https://wpms.test/ | grep wporg-two-factor

> curl -is https://wpms.test/users/iandunn/edit/account/ | grep wporg-two-factor
<link rel='stylesheet' id='wporg-two-factor-settings-style-css' href='https://wpms.test/content/plugins/wporg-two-factor/settings/build/style-index.css?ver=0.1.3' type='text/css' media='all' />

[adamwoodnz]

These styles are still being loaded on Showcase and affecting our performance scores

They're also being loaded on the WordPress.org homepage. Could we use the URI to determine whether to dequeue?

function maybe_dequeue_stylesheet() {
        // Allow to enqueue on the user settings page.
	if ( 0 === strpos( $_SERVER['REQUEST_URI'], '/support/users' ) ) {
		return;
	}

	wp_dequeue_style( 'wporg-two-factor-settings-style' );
}

[iandunn]

🤔 That's a good point. Fixed in #262 👍🏻