fix(useTextareaAutosize): support changes of element width

[dpschen]

Description

If the size of a textarea is changed by other stuff than the window width useTextareaAutosize currently breaks. By watching the textarea via useResizeObserver we make sure a change in width is accounted for.

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.