Update function-schemata sub-module to HEAD (6cf755c)

New changes:
eda2afd Remove mutex locks and async references in function schemata.
6bdb7c0 A first example of creating JS classes for ZObjects.
1c703e1 utils: Drop makeResultEnvelopeWithVoid, unused anywhere
7858c64 definitions: Adjust Z820/Trigger meta-data to have both key and value
6cf755c definitions: Add Z7015/Positive Integer type for natural language generation experiments

Bug: T296841
Bug: T309642
Change-Id: I6453b2a9d25284df64ed3d3a2c3c40c5d9474ec6