Drop jcommander

[jvalkeal]

For now leading to 2.1.x remove support for com.beust.jcommander. It doesn't provide that much value and has been problematic for stories to have graalvm support.

We may think to bring back better support model for adapters if there is a need for those. Thus, for now lets remove it.

[grahambrown11]

I just got the latest snapshot and now my project doesn't start - the autoconfigure spring.factories refs a now deleted class: org.springframework.shell.boot.JCommanderParameterResolverAutoConfiguration

[jvalkeal]

@grahambrown11 thx, just pushed a fix.