--nimargs: eg `choosenim 1.2.0 --nimargs -d:danger -d:nimEmulateOverflowChecks`
example use case: for users who need custom build options, eg: -d:nimEmulateOverflowChecks

ref: https://irclogs.nim-lang.org/05-04-2020.html#21:18:19
> If choosenim needs to compile Nim for you then you cannot pass that flag to it

## proposal
`chosenim option --nimargs [args...]`
which forwards as is arguments to nim compilation commands




