Add Prometheus scrape target server to Caliper manager

[CaptainIRS]

(This is just a draft implementation, discussions are ongoing in Discord)

Checklist

• [x] A link to the issue/user story that the pull request relates to
• [ ] How to recreate the problem without the fix
• [ ] Design of the fix
• [ ] How to prove that the fix works
• [ ] Automated tests that prove the fix keeps on working
• [ ] Documentation - any JSDoc, website, or Stackoverflow answers?

Issue/User story

#1353

Design of the fix

WIP

Validation of the fix

Automated Tests

WIP

What documentation has been provided for this pull request

WIP

[codecov[bot]]

Codecov Report

Merging #1434 (cc1f2a6) into main (64f3868) will decrease coverage by 0.27%. The diff coverage is 27.65%.

@@            Coverage Diff             @@
##             main    #1434      +/-   ##
==========================================
- Coverage   55.56%   55.28%   -0.28%     
==========================================
  Files         103      104       +1     
  Lines        4451     4495      +44     
  Branches      676      686      +10     
==========================================
+ Hits         2473     2485      +12     
- Misses       1435     1457      +22     
- Partials      543      553      +10     

Flag	Coverage Δ
caliper-core	44.07% <27.65%> (-0.25%)	:arrow_down:
caliper-fabric	80.46% <ø> (ø)
generator-caliper	83.62% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...lib/common/messengers/process/process-messenger.js	25.00% <ø> (ø)
...ackages/caliper-core/lib/manager/caliper-engine.js	7.60% <11.11%> (+0.37%)	:arrow_up:
...lib/manager/prometheus/prometheus-scrape-target.js	30.30% <30.30%> (ø)
...e/lib/manager/orchestrators/worker-orchestrator.js	20.51% <33.33%> (-0.09%)	:arrow_down:
.../lib/worker/tx-observers/prometheus-tx-observer.js	70.14% <50.00%> (+0.45%)	:arrow_up:

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