Add InserterPanel around block directory results.

[StevenDufresne]

Description

This PR addresses #21746 using the InserterPanel component.

How has this been tested?

Manual test by turning on Block Directory Experiment and searching for Boxer.

Screenshots

With Blocks:

Without Blocks:

Types of changes

This PR reestablishes the padding around the container but introduces 1 change. By using the InserterPanel component, a title had to be provided. I believe this helps in creating a consistent experiment but the copy should be scrutinized: Search Results.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[youknowriad]

From the first screenshot, I think maybe we should add a bit of padding between the panel title and the text "no blocks ..."

Change looks good though.

[StevenDufresne]

@youknowriad Cool. I update the padding/margin. We were forcefully removing it.

[youknowriad]

Looks great.

[youknowriad]

Just noticed that you've been using a fork of Gutenberg, you can use branches if you like as you're a member of the repo.

[StevenDufresne]

Cool!

Thanks for the heads up!

[StevenDufresne]

I kinda like the fork model because I don't need to worry about deleting branches. I can just kill my fork and move on.

[youknowriad]

From the reviewer's perspective, using a branch is easier (we can checkout it more easily), that said, if you prefer using a fork, that's not a reason to change.