[MOOSE-308] Terms Block Edits

[GeoffDusome]

What does this do/fix?

This PR fixes an issue @Vinsanity was having with Mediavine where a CPT existed with only one taxonomy assigned. This caused the onChange function of the SelectControl to never be able to be called, which meant the value was never correct for the block on this post type.

To fix, I've done the following:

• Set the default value from the taxonomyToUse attribute on the block to an empty string.
• Updated the SelectControl for taxonomyToUse to use a disabled option as it's default state. This means, unless set in a pattern or template, the block will always default to "no taxonomy selected".
• Cleaned up the edit.js file to use withSelect, as this is the intended way to grab information from the select API prior to rendering blocks.
• Updated the post.php and post-left-aligned.php patterns to specifically choose the category taxonomy as the default for those usages of the block (otherwise no taxonomy would be chosen when creating new posts).

Additionally:

• I updated some of the comments in the style files to be consistent with other blocks
• We are now disabling pointer events for links in the editor. You shouldn't be able to click any links within the block in the editor now.

QA

Links to relevant issues

• Link to Issue

Screenshots/video:

• Link to Video

[Vinsanity]

🟢 Very nice! Thanks Geoff.

[Vinsanity]

thank you!

[dpellenwood]

Nice improvement!