Add option to force a version when adding a mod

[rickiewars]

I came across a mod called Universal Perms which has no version targeting 1.21.5.
However, version 1.0.7 does work properly on Minecraft 1.21.5.
Adding an option like this would allow to install a specific version of a mod regartless if it would be compatible with the given Minecraft version.

Example usage:

mcpm add universal-perms 1.0.7 --force

Should only work when a specific version has been given.