Add support for libassuan file sockets (WinGnuPG support)

[Lexicality]

This PR fixes #2 to resolve #1.

I left @NZSmartie's commits untouched, but I can rebase and squash if you like.

[SidShetye]

When will we have a release with gpg support? Thanks!

[wizhippo]

I too would like a new release now that wsl 2 is almost out.

[Legion2]

Add me to the list of waiting people

[Lexicality]

Side note that my fork (wsl-relay) supports gpg and I've been using it with an edited version of Nimamoh's Script in WSL2 without problem