Bundled Themes: Update TT4 for 6.4 Beta 2.

Twenty Twenty-Four (TT4) updates for 6.4 Beta 2.

Changes include bugfixes from the theme's development repo since Beta 1 such as: 
* Renamed patterns and images
* Improved image descriptions
* Polished a few of the templates to fit better the design
* Addressed some a11y concerns.
* Changed the required version to 6.4, aligning it with the last few default themes since we are making use of some of the features that will make it to 6.4, such as aspect ratio.

Follow-up to [56726], [56721], [56716].

Props onemaggie, desrosj, mukesh27.
Fixes #59524.

git-svn-id: https://develop.svn.wordpress.org/trunk@56764 602fd350-edb4-49c9-b593-d223f7449a82

Author: hellofromtonya