When using the TouchScreenKeyboard in HoloLens2 to enter text into a uGUI InputField or TextMeshPro, clicking the 'Tab' on the keyboard doesn't insert tab characters.

Steps:

1. Open the attached Unity project
2. Build for Universal Windows Platform (UWP)
3. Open the generated Visual Studio sln and build/deploy to a HoloLens2 device or emulator
4. Once the app launches select the bottom InputField (multi-line)
5. When the TouchScreenKeyboard appears, enter some characters into the InputField
6. Click the '&123' key to switch to the Numbers/Symbols pane
7. Click the 'Tab' key in the upper left corner

Expected: a Tab character is inserted into the InputField
Action: nothing happens; it's impossible to insert a Tab

NOTE:
- Tab works fine when using the Desktop Windows 10 on-screen keyboard
- Don't test using the "single-line" InputField (topmost one); tabs are ignored in this UI
- This bug can be reproed on the HL2 emulator
- Probably also repros on Xbox One (UWP) as well but didn't test this scenario