Handle concurrent binary downloads using file locks

[EhabY]

Closes #575

[mafredri]

I'm not against the file locking implementation used here, but asking out of curiosity: would IPC communication between VS Code windows have been an option here, like with the login prompt?

Thanks for working on this ❤️, concurrent downloads has been a pain-point for me!

[EhabY]

would IPC communication between VS Code windows have been an option here, like with the login prompt?

@mafredri We could maybe use this for the progress monitoring but we definitely need a lock file since that would make crashes/staleness/stuck handling much simpler. Libraries like proper-filelock are already implemented to handle this. IPC communication using secrets might get a bit tricky and cumbersome to work with. Also, we already writing the binary to the file system, it only feels natural to use a filelock in the same folder 😉

[mtojek]

Thanks for addressing my comments! As long as other reviewers approve, you're good to go 👍

[mafredri]

Nothing to add, thanks for amending/answering my comments 👍🏻