Adopt the Mooniak Type glyphset definitions for Sinhala

https://github.com/mooniak/lanka-glyphsets defines a standard set of glyphs at four levels for fonts targeting Sri Lankan users. The kernel glyphset is currently complete, but the others are WIP.

Start by reviewing the Mooniak lanka-glyphsets repository linked in the issue and comparing its four Sinhala glyphset levels with the currently complete kernel glyphset. Done means the applicable standard definitions are adopted, while accounting for the linked project's note that the other levels are still work in progress.

Written by the indexing model from the issue text.