improvement: Update TextBoxComponent to use Snapshot mixin

[projectitis]

What could be improved

Update TextBoxComponent to use the Snapshot mixin.

Why should this be improved

It would simplify the TextBoxComponent code and re-use 'caching' code (maintaining caching code in one place).

Any risks?

Snapshot is new. Worst case is that we need to further improve Snapshot if it initially fails for the TextBoxComponent for any reason.

More information

See #2695