REST API: Always include `title.raw`/`content.raw` for Blocks in `context=view`.

Demarcations for reusable blocks are always expected to be accessible by clients.

Props noisysocks, youknowriad.

Merges [43917] to trunk.

See #45145 for the patch, #45098 for the original ticket.
Built from https://develop.svn.wordpress.org/trunk@44268


git-svn-id: https://core.svn.wordpress.org/trunk@44098 1a063a9b-81f0-0310-95a4-ce76da25c4cd