refactor: Merge duplicate input args

[nasdf]

Relevant issue(s)

Resolves #3045
Resolves #3042

Description

This PR merges the duplicate input args docID, docIDs, input, and inputs into a single list arg. With GraphQL input coercing the inputs can remain the same for lists as well as single items.

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?

Updated integration tests

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

• MacOS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.44%. Comparing base (701a7a5) to head (619e438).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3046      +/-   ##
===========================================
- Coverage    79.46%   79.44%   -0.02%     
===========================================
  Files          342      342              
  Lines        26529    26514      -15     
===========================================
- Hits         21080    21062      -18     
- Misses        3933     3938       +5     
+ Partials      1516     1514       -2     

Flag	Coverage Δ
all-tests	79.44% <100.00%> (-0.02%)	⬇️

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

Files with missing lines	Coverage Δ
client/request/mutation.go	100.00% <ø> (ø)
internal/planner/create.go	81.16% <100.00%> (-0.53%)	⬇️
internal/planner/delete.go	78.46% <100.00%> (ø)
internal/planner/group.go	87.18% <100.00%> (ø)
internal/planner/mapper/mapper.go	88.82% <ø> (-0.01%)	⬇️
internal/planner/select.go	85.11% <100.00%> (ø)
internal/planner/update.go	78.75% <100.00%> (+0.27%)	⬆️
internal/request/graphql/parser/mutation.go	85.92% <100.00%> (-0.93%)	⬇️
internal/request/graphql/parser/query.go	86.02% <ø> (-0.22%)	⬇️
internal/request/graphql/schema/generate.go	87.97% <100.00%> (-0.08%)	⬇️

... and 7 files with indirect coverage changes

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[fredcarle]

LGTM. I like that you kept the singular params. Thanks for this.

[shahzadlone]

LGTM