Add endColumn to output variables

[jbergstroem]

Seeing how snippets uses a column start/end to draw the tildes, perhaps this could also be exposed as endColumn? This way, graphical interfaces integrating actionlint can achieve a similar notation as the cli output.

$ actionlint
.github/workflows/lint.yml:27:9: shellcheck reported issue in this script: SC2016:info:1:20: Expressions don't expand in single quotes, use double quotes for that [shellcheck]
   |
27 |         run: |
   |         ^~~~

Current version

$ actionlint -format '{{json .}}' | jq
[
  {
    "message": "shellcheck reported issue in this script: SC2016:info:1:20: Expressions don't expand in single quotes, use double quotes for that",
    "filepath": ".github/workflows/lint.yml",
    "line": 27,
    "column": 9,
    "kind": "shellcheck",
    "snippet": "        run: |\n        ^~~~"
  }
]

With suggested change

$ actionlint -format '{{json .}}' | jq
[
  {
    "message": "shellcheck reported issue in this script: SC2016:info:1:20: Expressions don't expand in single quotes, use double quotes for that",
    "filepath": ".github/workflows/lint.yml",
    "line": 27,
    "column": 9,
    "endColumn": 13, 
    "kind": "shellcheck",
    "snippet": "        run: |\n        ^~~~"
  }
]

[rhysd]

Now end_column is included in the JSON objects, which indicates the column at the end of ^~~~~:

> ./actionlint -format '{{json .}}' test.yaml | jq
[
  {
    "message": "property \"unknown_prop\" is not defined in object type {arch: string; debug: string; name: string; os: string; temp: string; tool_cache: string; workspace: string}",
    "filepath": "test.yaml",
    "line": 7,
    "column": 23,
    "kind": "expression",
    "snippet": "      - run: echo ${{ runner.unknown_prop }}\n                      ^~~~~~~~~~~~~~~~~~~",
    "end_column": 41
  }
]

Note that end_column is equal to column when ^~~ is not shown due to some reason (for example, the error range is empty)

[rhysd]

v1.6.20 included this.