Support passing arbitrary flags to run_all_experiments.py via request_pr_exp.py.

[oliverchang]

Currently there is very little control over flags passed to PR experiments:

oss-fuzz-gen/ci/k8s/pr-exp.yaml

Line 34 in 3dd239a

command: ["/bin/bash", "report/docker_run.sh", "${GKE_EXP_BENCHMARK}", "${GKE_EXP_NAME}", "${GKE_EXP_FUZZING_TIMEOUT}", "ofg-pr", "${GKE_EXP_LLM}", "${GKE_EXP_DELAY}"]

We should ideally support piping arbitrary flags via request_pr_exp.py.

e.g.

request_pr_exp.py -p 123 -n NAME -- --model=foo --context 

[DonggeLiu]

Another issue about docker_run.sh is that it assumes the order of command line args.
This is a good opportunity to upgrade it to a Python script to allow more flexible args.