Uninstaller doesn't clean up Windows registry entries

Title says it all.

Tested with mailspring 1.7.2 and Windows 10 (1909 update).

(Originally posted by frodri on GitHub.)

Thanks for reporting this! I think that this is happening because this method here (Mailspring/main.js at 4b6c24fefa270d29ee5733d66f0885aae4e6e4e1 · Foundry376/Mailspring · GitHub) isn’t a full inverse of the --squirrel-install path above it. Someone with a Windows machine might be able to knock this out fast!

(Originally posted by bengotow on GitHub.)