Remove some unnecessary code after Solution changes (#431)

Remove some unnecessary code after Solution changes (#431)

The solution stores platform-dependent releases, hence the Environment
parameter is not needed at the moment of writing the corresponding lockfile.

A stray exception handler in Alr.Commands.Withing was unneeded and masking as a
regular error some Constraint_Errors that should escalate to the main handler
to be reported as unexpected internal errors.

Dead code in Alire.Utils that is not going to be useful again has been removed.