feat: Add P Counter CRDT

[fredcarle]

Relevant issue(s)

Resolves #2116

Description

This PR adds a Positive Counter CRDT type. It converts the PNCounter implementation to a Counter implementation that supports both PN and P counters.

Tasks

• I made sure the code is well commented, particularly hard-to-understand areas.
• I made sure the repository-held documentation is changed accordingly.
• I made sure the pull request title adheres to the conventional commit style (the subset used in the project can be found in tools/configs/chglog/config.yml).
• I made sure to discuss its limitations such as threats to validity, vulnerability to mistake and misuse, robustness to invalidation of assumptions, resource requirements, ...

How has this been tested?

make test

Specify the platform(s) on which this was tested:

• MacOS

[codecov]

Codecov Report

Attention: Patch coverage is 82.45614% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 75.59%. Comparing base (9938518) to head (916729d).

❗ Current head 916729d differs from pull request most recent head 204fdc9. Consider uploading reports for the commit 204fdc9 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2482      +/-   ##
===========================================
- Coverage    75.66%   75.59%   -0.08%     
===========================================
  Files          291      291              
  Lines        28072    28086      +14     
===========================================
- Hits         21240    21229      -11     
- Misses        5478     5498      +20     
- Partials      1354     1359       +5     

Flag	Coverage Δ
all-tests	75.59% <82.46%> (-0.08%)	⬇️

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

Files	Coverage Δ
client/ctype.go	93.55% <100.00%> (+0.44%)	⬆️
core/crdt/errors.go	33.33% <100.00%> (-16.67%)	⬇️
db/base/collection_keys.go	84.62% <100.00%> (ø)
request/graphql/schema/types/types.go	100.00% <ø> (ø)
merkle/crdt/counter.go	68.42% <85.71%> (ø)
merkle/crdt/merklecrdt.go	88.37% <85.71%> (+0.57%)	⬆️
core/crdt/counter.go	55.86% <77.78%> (ø)

... and 8 files with indirect coverage changes

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[shahzadlone]

Praise: Nice tests

Mostly questions. Looks good in first pass

[islamaliev]

LGTM. Just have a few minor comments