API for well aliasing

[berland]

fmu.config should provide an API for aliasing of wells, which usually have different names in RMS and Eclipse.

Configuration for aliasing should be in global_variables.yml, and should support both rule-based (to the degree possible) and explicit listing of alias names.

The API should both be able to answer queries pr. well, but should also be able to return alias lists in the format currently used in the FMU sphere (dictionaries, dataframes, etc) (rule-based alias configuration must probably fail here).

[berland]

https://github.com/equinor/subscript/blob/master/src/subscript/prtvol2csv/fipmapper.py is a first-implementation of this.