feat: Add ability to explain dagScanNode attribute(s).

[shahzadlone]

Relevant issue(s)

Resolves #479

Description

Adds the spans attribute for dagScanNode to be included in the returned explain graph response.

Example:

Request:

query @explain {
  allCommits (dockey: "test-key", field: "1") {
    links {
      cid
    }
  }
}

Response:

{
  "explain": {
    "selectTopNode": {
      "selectNode": {
        "filter": null,
        "commitSelectNode": {
          "dagScanNode": {
            "spans": []{
              {
                "start": "/test-key/1",
                "end":   "/test-key/2",
              }
            }
          }
        }
      }
    }
  }
}

Tasks

• I made sure the code is well commented, particularly in 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?

Integration tests locally and only CI. Specifically make test.

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

• Manjaro Flavor of Arch Linux Running in WSL2 on Windows 11

[codecov]

Codecov Report

Merging #560 (00a91d3) into develop (2c920a1) will increase coverage by 0.15%.
The diff coverage is 100.00%.

❗ Current head 00a91d3 differs from pull request most recent head 13ae9af. Consider uploading reports for the commit 13ae9af to get more accurate results

@@             Coverage Diff             @@
##           develop     #560      +/-   ##
===========================================
+ Coverage    56.17%   56.33%   +0.15%     
===========================================
  Files          121      121              
  Lines        14276    14291      +15     
===========================================
+ Hits          8020     8051      +31     
+ Misses        5557     5542      -15     
+ Partials       699      698       -1     

Impacted Files	Coverage Δ
query/graphql/planner/dagscan.go	78.60% <100.00%> (+4.95%)	⬆️
query/graphql/parser/filter.go	62.06% <0.00%> (ø)
query/graphql/planner/order.go
query/graphql/planner/sort.go	83.50% <0.00%> (ø)
query/graphql/planner/explain.go	68.96% <0.00%> (+5.17%)	⬆️
query/graphql/planner/commit.go	90.90% <0.00%> (+6.36%)	⬆️

[AndrewSisley]

Got a couple of comments for you, mostly in the tests.

[fredcarle]

Approving assuming you address Andy's todo 🙂

[AndrewSisley]

Looks good - thanks for expanding the tests (is a nitpick in there but no worries if left as is)