Add sdkman to concourse

[philwebb]

We should rewrite SDKman publish scripts so they can be run in concourse. We should also somehow detect the default version because we keep forgetting to change it.

[mbhave]

Detect the default version for?

[snicoll]

The current line (2.4.x) at the moment. See the if clause that was recently changed in the side project for more details.

We need that to tell SDKman which release is “current”.

[philwebb]

This line of the current script.

[mbhave]

Closed by 7b38b0e.