Add Show Links option to show links to block transformations

[bobbingwide]

For Show Transforms, if Show Links is selected the idea is to produce a link to the target block's documentation.

In blocks.wp-a2z the format of the link is a hyphen separated concatenation of the US English block title with the full block name, prefixed by block/

See oik-blocks for logic that does something like this.

e.g. For the Spacer block it's block/spacer-core-spacer

In WordPress.org it's the hyphen separated block title, appended by block or embed, and prefixed by support/article/.

e.g. For the Spacer block it's support/article/spacer-block.

For Twitter embed it's support/article/twitter-embed