chore(linter): fix import resolver to support condition-only export map

[Renegade334]

The override from #1000 only supported pathy export maps, e.g.

{
  ".": "./index.js",
  "./conditional": {
    "import": "./conditional.mjs",
    "default": "./conditional.cjs"
  }
}

rather than

{
  "import": "./index.mjs",
  "default": "./index.cjs"
}

Unblocks #1132.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.31%. Comparing base (4d967bf) to head (4aca985).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1136      +/-   ##
==========================================
- Coverage   57.32%   57.31%   -0.01%     
==========================================
  Files          53       53              
  Lines       10368    10367       -1     
==========================================
- Hits         5943     5942       -1     
  Misses       4425     4425              

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