Move EvaluationLibrary's remaining functionality to Distribution (copying or removing platform-specific behavior)

[edwardpeters]

Feature Request

EvaluationLibrary.scala, and its platform specific variants, should be removed. Loading distributions should be on the Distribution companion object.

Description of Problem:

This fils is old and vestigial. The core of its functionality was removed long ago, and it only endures because it implements the platform specific behavior needed to work around a js compatibility issue (which hopefully will cease to be a problem soon.)

Potential Solutions:

Remove EvaluationLibrary
Add loading code to Distribution
If ZIO does not have cross-compiling file support by the time this is done, include platform specific supertraits of Distribution