Rename the `only_ddpl` keyword arg of determine_suitable_varinfo

[mhauru]

It should be called only_dppl since it's short for DynamicPPL. Both in src/experimental and in ext/DynamicPPLJetExt.jl.

[elsakarvouni]

could you please assign me this issue?

[mhauru]

Sure thing, done. Let me know if you need any help. It's really only renaming that is needed, and a bump of patch version number, since the relevant functions aren't exported.

[penelopeysm]

Closed by #1106