Add Find and Replace Functionality to Text Editors
This is a Epic to implement a Find and Replace functionality within the Text Editors at GitLab.
It's particularly useful to find and replace placeholders in templates (such as the `<feature-flag-name>` ).
Slack thread: https://gitlab.slack.com/archives/C0NFPSFA8/p1724938895922889
## Designs
{width=660 height=404}
[❖ View working file in Figma →](https://www.figma.com/design/IKYZhcvLSF57nCFtbw8gJJ/Text-Editors?node-id=1-113&t=xSGpPayxylchgtv1-1)
### Implementation plan
* [x] [Introduce feature flag + basic find](https://gitlab.com/gitlab-org/gitlab/-/issues/481892)
* [ ] Update documentation
* [ ] [Add tracking](https://gitlab.com/gitlab-org/gitlab/-/issues/505700)
* [x] [Add a counter e.g `2 / 5`](https://gitlab.com/gitlab-org/gitlab/-/issues/505694)
* [ ] Update documentation
* [x] [Add find next and prev buttons](https://gitlab.com/gitlab-org/gitlab/-/issues/505695)
* [ ] Update documentation
* [x] [Add a highlight for the searched keyword](https://gitlab.com/gitlab-org/gitlab/-/issues/505696)
* [ ] Update documentation
* [x] [Add close button](https://gitlab.com/gitlab-org/gitlab/-/issues/549067)
* [x] [Add replace text input with the icon on the left to toggle (single replace)](https://gitlab.com/gitlab-org/gitlab/-/issues/505697)
* [ ] Update documentation
* [x] [Add button to replace all](https://gitlab.com/gitlab-org/gitlab/-/issues/505698)
* [ ] Update documentation
* [x] [Add functionality to toggle case sensitivity](https://gitlab.com/gitlab-org/gitlab/-/issues/505699)
* [ ] Update documentation
* [ ] [Add the same functionality to rich text editor](https://gitlab.com/gitlab-org/gitlab/-/issues/504413)
* [ ] Update documentation
* [ ] Add tracking
* [ ] [Remove feature flag](https://gitlab.com/gitlab-org/gitlab/-/issues/504599)
* [ ] Update documentation
epic