Move job-related code to a single module

[s-vitaliy]

Part of #144

Scope

Implemented:

• Job-related services moved to a separate package
• Added struct metadataConfigurator which enriches job with stream metadata (id and kind).
• Added struct backfillConfigurator which enriches job with backfill metadata (true or false).

Checklist

• GitHub issue exists for this change.
• Unit tests added and they pass.
• Line Coverage is at least 80%.
• Review requested on latest commit.

[github-actions]

go-test-coverage report:

  below threshold:				coverage:	threshold:
  configuration/configuration.go		 0.0% (0/18)	70%
  services/job/backfill_configurator.go		16.7% (3/18)	70%
  services/job/metadata_configurator.go		 4.8% (1/21)	70%
  services/job/stream_context_configurator.go	53.8% (7/13)	70%
  telemetry/app_metrics.go			 0.0% (0/9)	70%

Package coverage threshold (70%) satisfied:	FAIL
  below threshold:				coverage:	threshold:
  services/job					21.2% (11/52)	70%
  telemetry					 0.0% (0/9)	70%
  configuration					 0.0% (0/18)	70%

Total coverage threshold (75%) satisfied:	FAIL
Total test coverage: 65.8% (244/371)

Files with uncovered lines:
  file:							coverage:	uncovered lines:
  configuration/configuration.go			0%		17-20 22-24 27-36 39-41 43-47 52-55 60
  services/controllers/stream/stream_definition.go	80%		71-73
  services/controllers/stream/stream_reconciler.go	83.5%		38-48 51-56 59-70 72 181-185 273-276 280-283 290-292
  services/controllers/stream/streaming_job.go		87.5%		12-14
  services/controllers/stream/unstructured_wrapper.go	73.1%		46-48 50-52 55-57 67-70 72-75 84-86 146-148 151-153 156-158 161-163 166-168 175-177 179-181 184-186 189-191 199-204 211-213 215-217 224-229
  services/controllers/stream_class/stream_class.go	81.4%		38-40 45-47 65-68 90-98 133-136
  services/job/backfill_configurator.go			16.7%		23-31 35-42 45-50
  services/job/metadata_configurator.go			4.8%		20-23 25-29 31-34 36-42 45-52 55
  services/job/stream_context_configurator.go		53.8%		24-31 33-36
  telemetry/app_metrics.go				0%		18-22 24 53-56 60-63 65