Tiled Gallery Block: Add a style extension to core gallery block to allow tiling

[glendaviesnz]

This is currently just a PoC to look at options for enhancing the core block and deprecating the tiled gallery block as a way to get the captions outlined in #11794 and reduce duplication.

Changes proposed in this Pull Request:

• Add a style option to core gallery block

Testing instructions:

• Check out PR, add a core gallery block and select the 'Tiled' style option
• The tiled layout has a repeating pattern after 30 images, so if you add more than 30 images you will see the full extent of the layout

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello glendaviesnz! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer and confirm D46336-code works as expected before merging this PR. Once this PR is merged, please commit the changes to WP.com. Thank you!
This revision will be updated with each commit to this PR

[jetpackbot]

	Warnings
⚠️	The PR is missing at least one [Status] label. Suggestions: [Status] In Progress, [Status] Needs Review
⚠️	"Proposed changelog entry" is missing for this PR. Please include any meaningful changes
⚠️	The Privacy section is missing for this PR. Please specify whether this PR includes any changes to data or privacy.

This is an automated check which relies on PULL_REQUEST_TEMPLATE. We encourage you to follow that template as it helps Jetpack maintainers do their job. If you think 'Testing instructions' or 'Proposed changelog entry' are not needed for your PR - please explain why you think so. Thanks for cooperation 🤖

E2E results is available here (for debugging purposes): https://jetpack-e2e-dashboard.herokuapp.com/pr-16476

Generated by 🚫 dangerJS against 624257e

[glendaviesnz]

FYI - currently the grid styling only works in the editor, not the front end - will sort that tomorrow

[glendaviesnz]

Closing this in favour of WordPress/gutenberg#23929