Provide standalone Java support #2307
Description
it was previously available in VS Code Camel K but this feature was not mirgated.
at time of implementation, standalone Java files was available only for Camel K. it is now available for Camel JBang too.
then it makes sense to move the code to the Language Support extension.
Note that several improvements were made since implementation, like VS Code JBang and some improvements in VS Code Java API.
It will be interesting to investigate if we can leverage them to have a smoother experience.
Note that given Camel K is no more part of Red Hat support, we should migrate to Camel JBang instead of kamel at the same time
see comments on https://issues.redhat.com/browse/FUSETOOLS2-2130 for implementation ideas and problems