[iOS] keyboard shift/delete icons and text colors

**Is your feature request related to a problem? Please describe.**

1. shift/delete key
in iOS keyboard, keyman keyboard shift and delete button icons look different than the system keyboard.

2. text colors
The text color for menu's "123"/ "abc" "space/keyboard name", globe icon and return key should be black similar to iOS system keyboard.

3. return key
Instead of the return key icon, we should have "return" in black color.
This word "return" should also change with context, "search", "tweet", "next", etc similar to system keyboard.

**Describe the solution you'd like**

**Product context**
- OS: iOS 13.3