Displays characters remaining and characters over limit

feat(GlFormTextarea): add support for character count

Closes #1243

See merge request !4097



Merged-by: Scott de Jonge <sdejonge@gitlab.com>
Approved-by: Andrew Fontaine <afontaine@gitlab.com>
Approved-by: Austin Regnery <aregnery@gitlab.com>
Approved-by: Scott de Jonge <sdejonge@gitlab.com>
Reviewed-by: Andrew Fontaine <afontaine@gitlab.com>
Reviewed-by: Scott de Jonge <sdejonge@gitlab.com>
Co-authored-by: Peter Hegman <phegman@gitlab.com>

chore(deps): update dependency cypress to v13.8.0

See merge request gitlab-org/gitlab-ui!4108



Merged-by: Scott de Jonge <sdejonge@gitlab.com>
Approved-by: Scott de Jonge <sdejonge@gitlab.com>
Co-authored-by: GitLab Renovate Bot <gitlab-bot@gitlab.com>

chore(deps): update dependency eslint-plugin-cypress to v2.15.2

See merge request gitlab-org/gitlab-ui!4104



Merged-by: Simon Knox <simon@gitlab.com>
Approved-by: Simon Knox <simon@gitlab.com>
Co-authored-by: GitLab Renovate Bot <gitlab-bot@gitlab.com>

# [78.19.0](gitlab-org/gitlab-ui@v78.18.0...v78.19.0) (2024-04-22)

### Features

* **GlFormTextarea:** add support for character count ([1b359aab](gitlab-org/gitlab-ui@1b359aab))