Introduce immutable Function id's

Feature Requests
1

Current

Functions are defined and queried byName
Function.byName("addTwo") & addTwo(). Renaming a Function name leads to error-prone manual updating of all Fauna Functions referencing the renamed Function.

Expected behavior

Fauna takes care of keeping all references in sync for me.

For that, Fauna could introduce an immutable ID in addition to the function’s name.

Function.byName("addTwo") & addTwo() will resolve under the hood to Function.byId("386162354298028236").
With that, functions can be safely renamed while fauna can ensure that all functions that reference these functions still keep the correct reference.