feat(model): support named parameters in Model.findOne

[swayamsingh2004]

Summary

Adds support for calling Model.findOne with a single named-parameters object, in addition to the existing positional arguments. Addresses #10367, scoped to Model.findOne as a first step (per discussion in the issue).

Approach

Per the discussion in #10367, named parameters are detected using an internal namedParamsSymbol (added to lib/helpers/symbols.js, following the same pattern as existing internal symbols like modelCollectionSymbol). This avoids any ambiguity with real schema field names like filter, projection, or options, since a Symbol key can never collide with a string key.

Example

// existing positional style (unchanged)
User.findOne({ email: 'x@y.com' }, 'name', { lean: true })

// new named-parameters style
User.findOne({
  [namedParamsSymbol]: true,
  filter: { email: 'x@y.com' },
  projection: 'name',
  options: { lean: true }
})

Testing

• Added a test in test/model.querying.test.js covering both the old positional style and the new named-parameters style.
• Ran the full test suite locally (npm test): 4378 passing, 0 failures (one unrelated pre-existing flaky timeout in timestamps.test.js that passes in isolation).