PipeScript should be able to define [Aliases]

[Alias()] is wonderful, but currently does not allow for a dynamic value.

PipeScript should create a transpiler for [Aliases]

When used within a [Parameter()] attribute, [Aliases()] should output a new [Alias] attribute with the result.

When used against a [VariableExpressionAst], [Aliases()] should output a series of Set-Alias commands.
