Signature help for calling .NET methods

[felixfbecker]

Summary of the new feature

When calling .NET methods in PowerShell scripts, I would like to see signature help. I can see the signature in the completion info, but not once I typed the (.

[TylerLeonhardt]

This is actually a dupe of PowerShell/PowerShellEditorServices#13. It's been around for a while and is something that everyone would enjoy.

We'll get to this as soon as we can... however we're spread quite thin at the moment

[rjmholt]

Going to close this as a duplicate of #1356.