Add support for heading alignment buttons

[SergioEstevao]

Fixes #1880

Gutenberg PR: WordPress/gutenberg#20745

This PR updates the GB reference to add support to alignment on the Heading block.
In the process, the heading block was refactored to share all the edit method with the web and that that involved using the new Text component that needed the adding of the emotion style library.
We now have support for dropdown menu in the block control. The implementation uses a BottomSheet to show the options when tapped.

To test:

• Open the demo app
• Add a Heading block
• Check if the alignment options are visible on the block toolbar
• Check if the alignment options work correctly.
• Check if the header size show and work correctly on the toolbar

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[iamthomasbishop]

Thank you for working on this! It'll be beneficial for a bunch of blocks/features <3

[SergioEstevao]

@mchowning is going to check why the align commands don't work on Android.

[mchowning]

I have opened an AztecEditor-Android PR that should address the alignment issue we're seeing here on Android.

[marecar3]

We're freezing 1.24.0 today. If you think it is ready and if you'd like to ship it with 1.24.0please merge it into develop branch. Otherwise, we can bump it to 1.25.0. @SergioEstevao @Tug

[Tug]

[SergioEstevao]

I'm merging this PR and doing a follow up PR to disable the options to align in Android if Aztec Android is not until next Friday.