Clean the top-level of the /build folder

[tarhi-saad]

After the changes introduced in the #6737 PR, the /build folder is currently polluted with so many top-level folders. To fix this, we can choose to generate the Inner Blocks blocks.json files inside a parent folder (e.g., /checkout-blocks and /cart-blocks).

This is the code block to update:

woocommerce-blocks/bin/webpack-configs.js

Lines 264 to 277 in b220e49

	from: './assets/js/blocks/**/block.json',
	to( { absoluteFilename } ) {
	/**
	* Getting the block name from the JSON metadata is less error prone
	* than extracting it from the file path.
	*/
	const JSONFile = fs.readFileSync(
	path.resolve( __dirname, absoluteFilename )
	);
	const metadata = JSON.parse( JSONFile.toString() );
	const blockName = metadata.name
	.split( '/' )
	.at( 1 );
	return `./${ blockName }/block.json`;

[senadir]

This fix wouldn't affect JS translation loading (only concerns PHP translation loading) so it's fine to fix without backward compatibility.