support `meta` block in workflow body as well as task about wdl

[geoffjentry]

This is interesting, I didn't know anyone ws using the meta block, I'm glad it gets some love.

@kcibul I suspect this should be a super easy change

[patmagee]

I +1 this and would love if it was extended to the parameter_meta as well. We were thinking that we may have to parse comments to attain this information, but if these blocks are implemented it would greatly be appreciated

[geoffjentry]

@delocalizer @patmagee I put together a quick PR on wdl4s to take care of this. Once it's in I'll update cromwell & wdltool so it'll be live. It turned out I was wrong in that the scala objects were aware of these blocks but it doesn't exit wdl4s so the other software only needs to update their dependency.

[delocalizer]

thanks @geoffjentry, closed by broadinstitute/wdl4s#53