Lint detail should not contain the line number

[crazy-max]

When using --print=lint, detail field contains the affected line number such as (line 2):

{
    "warnings": [
      {
        "ruleName": "SelfConsistentCommandCasing",
        "description": "Commands should be in consistent casing (all lower or all upper)",
        "detail": "Lint Rule 'SelfConsistentCommandCasing': Command 'frOM' should be consistently cased (line 2)",
        "location": {
          "ranges": [
            {
              "start": {
                "line": 2
              },
              "end": {
                "line": 2
              }
            }
          ]
        }
      },
      ...
}

Sounds repetitive as this information is already available in location. This is also important if we want to use this field through GitHub annotations or other tool that already put the caption on the right line:

cc @daghack @tonistiigi