Notes iteration for WordPress 7.1

Following on from the work in https://github.com/WordPress/gutenberg/issues/66377 and https://github.com/WordPress/gutenberg/issues/73260 for the last two respective releases, this issue serves as the iteration issue for Notes enhancements, tasks, and bug fixes planned for WordPress 7.1.

• Support for Notes on specific content within a block (Inline block commenting #59445)
• Support for Notes on content across more than one block (e.g., text spanning multiple paragraph blocks) (https://github.com/WordPress/gutenberg/issues/73416)
• Add support for rich text to Notes (https://github.com/WordPress/gutenberg/issues/73413)
• Sending notifications for Notes (beyond what was achieved in https://github.com/WordPress/gutenberg/issues/73030, beginning with https://github.com/WordPress/gutenberg/issues/72184). This should include for mentions, responses, follow a note.
• Minified Notes experience (https://github.com/WordPress/gutenberg/issues/73417)
• Add "apply suggestions" feature to Notes (https://github.com/WordPress/gutenberg/issues/73411)
• Introducing a new "Suggestion mode" tool for exposing Notes features (https://github.com/WordPress/gutenberg/issues/73410)
• Add emoji reactions to Notes (https://github.com/WordPress/gutenberg/issues/75144, https://github.com/WordPress/gutenberg/pull/75549)

Designs

Pulling from @jasmussen lovely comment here, below are some designs for implementing aspects of the above scope.

Adding notes, even inline

Make a selection, click the floating button (or we add a button in the main block toolbar). Notes can exist in the canvas even with a sidebar open.

Managing notes

The notes