[Intent to Remove] Remove Rhino (Less Java) and refactor #2985

[matthew-dean]

It's very unlikely the less-rhino adapter in this repo actually functions, or functions as expected. It should be removed and the Nashorn PR at #2985 should be refactored.

My proposal is that Nashorn support is a separate repo with less as a dependency (as mentioned on that thread), such that the "Less Java" repo is at https://github.com/less/less-java. BUT this is contingent on a dedicated Java developer taking on this work of both
a) migrating that PR
b) being the core maintainer of less-java

Either way, no one seems to be active in maintaining Rhino, so it needs to be removed.

[matthew-dean]

Open Rhino issues: #2005 #2044 #2316