Support json as robot framework output

[siongwai]

Hi,

I would like to ask for support json file as RF output.

RF 7.2 has added output file format to json, it is nice if pabot able to support json file as RF output.

command: pabot --output output.json .\tests\test.robot

This is the error message when trying to run pabot with json output file

Robot Framework remote server at 127.0.0.1:8270 started.
Storing .pabotsuitenames file
2025-01-16 23:32:36.504106 [PID:27396] [0] [ID:0] EXECUTING Test
2025-01-16 23:32:41.551500 [PID:27396] [0] [ID:0] PASSED Test in 5.0 seconds
WARN: No output files in ".\pabot_results"
0 tests, 0 passed, 0 failed, 0 skipped.
===================================================
Output:
[ ERROR ] Reading XML source '' failed: No such file or directory

Try --help for usage information.
Stopping PabotLib process
Robot Framework remote server at 127.0.0.1:8270 stopped.
PabotLib process stopped
Total testing: 5.0 seconds
Elapsed time:  5.73 seconds