Create & Expose Settings Components

[ckanitz]

As the "gutenberg data store" is not loaded automatically by using "rest-sensitive" components we had to rewrite some of our existing components in some of our latest projects:

• Post/Entits Select Control -> Post Select Setting
• Weblink Control -> Weblink Setting
• Image Select Control -> Media Select Setting

Those Setting Components are basically the same as the Control counter-part. They differ in data fetching:

• Controls: Data-Store
• Setting: fetch(REST_URL ...)

For future development we might want to transfer those Setting Components to the Basic Plugin and expose them.
Thus we won't need to add the to every project in the future.

If you green light this just assign me and change the label(s).