Custom Margin and Paddign Settings

[MuluhGodson]

Fixes

Fixes https://github.com/creativecommons/project_creativecommons.org/issues/121 by @brylie

Description

This PR adds padding and margin controls to the core/columns block, core/column block and core/group block. Other blocks can easily be added by adding them to the custom-block-settings.js file in the enableSpacingControlOnBlocks array.

I used v2 of theme.json but this didn't work (unsure why) but since v1 is still supported it can be used in the mean time and subsequently update to v2.

Screenshots

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[brylie]

Having the padding panels is already a good move :-)

[brylie]

Let me know when this is ready for review.

[brylie]

@MuluhGodson, it looks like there is still a minor conflict in functions.php