Add Amharic keyboard layout

This merge request adds support for an Amharic keyboard layout with pre-edit based Ge'ez fidel composition..

Overview of the Ge'ez (Amharic) script

• the script contains 26 base characters.
• Each base character has 7 variations depending on the vowel modification.
• Example : ሀ (base character) - ሀ ሁ ሂ ሃ ሄ ህ ሆ

Current behavior:

• Pressing a base fidel displays its fidel family in the candidate list.
• The pressed base fidel is stored as preedit text.
• Selecting a candidate commits the selected fidel.
• Pressing another base fidel automatically commits the existing preedit text before starting a new composition.

Screenshots or screen recordings