removed unity interface

Description

Removed BurtSharp.UnityInterface. This will be located in https://git.barrett.com/burt/software/burt-sharp-unity

See https://git.barrett.com/burt/software/burt-sharp-unity/merge_requests/1

What to focus on

• put content here.

Reviewers

• @alexluleme
• @amyblank
• @bz
• @cw
• @ps
• @wd

Resources

Issues

What issues does this fix?

• Fixes #issue-number