chore: Strip DSKey prefixes and simplify NewDataStoreKey

[fredcarle]

Relevant issue(s)

Resolves #943
Resolves #799

Description

The PR returns NewDataStoreKey to its simplest form of element indexing requiring the provided key string to be either 3 (Object Marker) or 4 elements. To accomplish this we made sure that the return datastorekey strings were stripped of prefixes.

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

Merging #944 (29e412e) into develop (0b9719f) will increase coverage by 0.01%.
The diff coverage is 76.59%.

@@             Coverage Diff             @@
##           develop     #944      +/-   ##
===========================================
+ Coverage    60.29%   60.30%   +0.01%     
===========================================
  Files          164      164              
  Lines        17700    17712      +12     
===========================================
+ Hits         10672    10682      +10     
- Misses        6081     6082       +1     
- Partials       947      948       +1     

Impacted Files	Coverage Δ
db/fetcher/fetcher.go	60.43% <40.00%> (-0.63%)	⬇️
db/collection.go	66.10% <50.00%> (-0.26%)	⬇️
datastore/wrappedStore.go	66.01% <82.35%> (+1.77%)	⬆️
core/key.go	87.50% <89.47%> (+2.25%)	⬆️

[AndrewSisley]

Looks good - thanks for fixing this :)