Fix Sinhala keyboard layout

This CL modifes the following points.
- add digit hint letters on the 1st row.
- remove digit more keys from shifted layout.
- use normal font for Sinhala letters.
- use auto X scale flag to fix Sinhala letters on a key top.

Bug: 6911143
Change-Id: I082ea38529399dce7d99c980e2be07c35d2e912d