Adds `Str:: convertCase()` (#326)
* Adds `Str:: convertCase()`
Co-Authored-By: Deeka Wong <8337659+huangdijia@users.noreply.github.com>
* Cs Fix
Co-Authored-By: Deeka Wong <8337659+huangdijia@users.noreply.github.com>
---------
Co-authored-by: Deeka Wong <8337659+huangdijia@users.noreply.github.com>