Follow-up to [#52432][]
Related to [#52430][]

Helpers like `text_area_tag` construct [textarea][] elements. This
commit renames all view helper and form builder methods to replace
occurrences of `text_area` with `textarea`.

In the same style, this commit also renames the `rich_text`-prefixed
helpers to utilize a `textarea` suffix instead of the existing
`text_area` suffix.

To preserve backwards compatibility, this commit defines aliases for the
existing `text_area` format.

[#52432]: https://github.com/rails/rails/pull/52432
[#52430]: https://github.com/rails/rails/issues/52430
[textarea]: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/textarea