Fix some of our exclusion for rat

[ebarboni]

Once Apache NetBeans is build you cannot use ant rat without license issue as some of generated code is not excluded.
On the maven plugin it's possible to exclude according to .gitignore but I did'nt succeed with ant.
Not sure the approach is correct but here is a fix.

ignore the following=>
generated code from ANTLR
in hcl languages
build artefacts
.gradle cache

Added a Header
missing header was detected on a test file in java.lsp

Maybe the jenkins jobs [1] could be patched to do a ant build before a ant rat verify-libs-and-licenses so we could anticipate the missing rules in rat file.

[1]https://ci-builds.apache.org/job/Netbeans/job/netbeans-license/

[neilcsmith-net]

Makes sense. Although the important thing is that rat passes on the sources before a build. Having it still pass after a build is useful, but not essential IMO.

[matthiasblaesing]

Looks sane to me.