Allow `-t/--targets` to accept JSON array on stdin

[jay7x]

Use Case

I'd like to filter nodes in the inventory with a plan and pass the node list to another plan as a targets list. For example:

bolt plan run inventory::filter variable=pp_role value=sandbox | \
bolt plan run example::foo -t-

The only value bolt plan run prints on stdout is the plan result value, which is always printed as JSON:

bolt plan run inventory::filter variable=pp_role value=sandbox
[...]
[
  "node1.example.tld",
  "node2.example.tld",
]

Describe the Solution You Would Like

With all the above in mind, the best solution is to teach bolt -t- to understand if JSON is given on stdin, I guess.

Describe Alternatives You've Considered

1. Use jq -r between bolt invocations to convert from JSON array to the plain text list.
2. Use --params=- instead of -t- and pass targets there.. Though, it makes passing other parameters to the 2nd plan much more complicated. One need to merge JSON documents for this.