Allow filtering the alignment options of blocks via `theme.json`

Related https://github.com/WordPress/gutenberg/issues/34316

The align options of blocks can be filtered using the [block_type_metadata](https://developer.wordpress.org/block-editor/reference-guides/filters/block-filters/#block_type_metadata) filter. It'd be easier for themes if they could filter those options via `theme.json` as we do with other settings such as `units`.
