PTFM-9636: Add tests for dx run --clone with systemRequirements

Also cache and display cloned job's systemRequirements in the new
job's details.
Refine dx run input flag behavior

* Make --input-json/--input-json-file override a cloned job's input
* Document change in dx run --input-help
* Pipe dx run --input-help to less if possible
* Add tests