Drag and drop does not work for WSL because paths are pasted as windows
paths having incorrect path separator and path root. This PR adds code
to correct the path in TerminalControl before pasting to WSL terminals.
One problem with this approach is that it assumes the default WSL
automount root of "/mnt". It would be possible to add a setting like
"WslDragAndDropMountRoot"... but I decided it if someone wants to change
automount location it would be simple enough just to create the "/mnt"
symlink in WSL.
## Validation
Couldn't find an obvious place to add a test. Manually tested
cut-n-paste from following paths:
- "c:\"
- "c:\subdir"
- "c:\subdir\subdir"
- "\\wsl.localhost\<distro>"
- \\wsl.localhost\<distro>\subdir"
Closes#331
d5974f4c91