(Re)Implement QueryJSON as LogMsg emitter

[radeksimko]

Alternative Solutions

I have also considered implementing this via iter.Seq which would make for a simpler interface that caller can just range over but that would probably imply ignoring any and all errors associated with reading and parsing individual messages, which does not seem like an ideal design.

TODO

• Manually test with any provider known to implement lists
• Add unit tests

[SBGoods]

@rainkwan and I just tested these changes along with the new tfjson changes in terraform-plugin-testing and I think we're encountering a deadlock at the wg.wait() in runTerraformCmd() because the pw writer pipe that was defined is blocked waiting on the pr reader pipe to read.

[radeksimko]

@SBGoods I am aware and working through resolving that.

[hashicorp-cla-app]

All committers have signed the CLA.

[radeksimko]

TBD: We could surface these somehow through additional methods or fields on LogMsgEmitter though that makes them time/ordering dependent. Perhaps it's obvious that you can't possibly have such errors until you have finished reading the last message but perhaps it's not.

Also we should probably work out what these errors could possibly be and what is the likelihood of them occurring all at the same time - i.e. whether we really need 3 separate fields/methods for those or whether we can just have 1.

[radeksimko]

This part of the comment is actually no longer true as it relates to earlier version of the code.

I'm still unsure where exactly it is best to close the stdout reader and how/whether to surface the error from that.