Removed `target="_blank"` from Browser Uploader Link

[dilipbheda]

While visiting the wp-admin/media-new.php page, I noticed that the Browser Uploader link included an unnecessary target="_blank" attribute.

Reason for Removal:

The Browser Uploader link does not navigate to a new page, it simply toggles the browser uploader section dynamically without reloading the page. Therefore, the target="_blank" attribute is redundant and should be removed.

[sabernhardt]

Yes, the browser uploader link apparently stays on the same page, behaving more like a button, unless you purposely open it in a new tab (with Ctrl+click or similar).

• The ​script uses .preventDefault() and hides the multi-file uploader by ​adding the `html-uploader` class.
• With Javascript disabled, the link is hidden (using the ​`hide-if-no-js` class).

For the patch, I would prefer to keep the translatable string as it is, replacing target="_blank" with an empty string. Then translators would not need to update anything, and the current string would still be available in case a future change requires additional attributes.

printf(
	/* translators: 1: URL to browser uploader, 2: Additional link attributes. */
	__( 'You are using the multi-file uploader. Problems? Try the <a href="%1$s" %2$s>browser uploader</a> instead.' ),
	$browser_uploader,
	''
);

However, if changing the string is important, it would only have one %s placeholder:

printf(
	/* translators: %s: URL to browser uploader. */
	__( 'You are using the multi-file uploader. Problems? Try the <a href="%s">browser uploader</a> instead.' ),
	$browser_uploader
);

[joedolson]

Good catch, @dilipbheda!

I'm thinking that we should also semantically change this to a button. To keep things simple, we might want to just add role="button" and add the extra key handler to the events to support spacebar triggering.

That would also continue to allow users to open in a new tab if they are accustomed to doing that, though I wonder how often that actually happens...