Account for servers having multiple users working on the same project

[grizzlyism]

If multiple users are working on the same server and enable the "show Branch", only one user can write to this file:

/tmp/.vscode-projects-plus_branch-git-cache.json.

Can you please allow a user to customize this file's location in vscode Settings or settings.json?

Thank you

[fabiospampinato]

PR welcome for prepending the user name to those kind of files.