Make it possible to install different versions of VLS

[octref]

Branching off #750

Currently we don't do any Continuous Release, so until we release on marketplace, people who are bugged with specific issue would have trouble getting the latest fix.

However, most issues people have could be solved by updating fixes checked into VLS. Maybe we can hookup the CI to do daily VLS releases like TypeScript does, and make it possible for user to run a command (VS Code / CLI command) to upgrade VLS.

[octref]

Not much benefit...People probably just wanted. #682.