Add withUrlParams to JobSource

[crioux-stripe]

Context

We submit most of our jobs similar to Netflix with target parameter being submitted as part of the submission payload. However we also want to inject runtime details like which availability zone the worker is in that can only be known at runtime. This change would allow users to inject this sort of runtime info MantisJob.source(new JobSource().withUrlParams(myUrlParams)).stage(...) while still otherwise parsing the target param from Context.

cc @tcai-stripe

Checklist

• ./gradlew build compiles code correctly
• Added new tests where applicable
• ./gradlew test passes all tests
• Extended README or added javadocs where applicable

[github-actions]

Test Results

622 tests  ±0   612 ✅ ±0   8m 6s ⏱️ +5s
142 suites ±0    10 💤 ±0 
142 files   ±0     0 ❌ ±0 

Results for commit dad586e. ± Comparison against base commit 1ffc3b9.