Block Editor: Allow a theme to override settings per block for editor features

[gziolo]

Description

Related to #22622.

Follow up for #22291 where initial handling for block editor features were introduced.

Usage:

// edit.js

const Edit = ( props ) => {
    const isDisabled = ! useEditorFeature( 'typography.dropCap' );
    // ...
};

Based on that idea, it included block level overrides for features using the following definition of the block:

registerBlockType( 'my/block', {
    supports: {
        __experimentalFeatures: {
            typography: {
                dropCap: true,
            }
        },
    },
    // ... everything else
} );

The idea is to take it to the next level – a theme should be able to disable any editor feature for the selected block using experimental-theme.json config file specific for the theme.

The full proposal from @nosolosw in #22291 (review).

[youknowriad]

how is this different from #22655

[gziolo]

We can consolidate into one if your prefer. The difference is that:

• this PR – individual block level
• Block Editor: Allow a theme to override global defaults for editor features #22655 - global level - all blocks affected