Don't duplicate Lambda Event Params

[sternetj]

With version 7.0.1 a query string like ?a=1&a=2&b=3 would produce params like

{
	queryStringParameters: { a: '1,2', b: '3' },
	multiValueQueryStringParameters: { a: ['1', '2'], b: ['3'] },
}

This change causes it to produce params like

{
	queryStringParameters: { b: '3' },
	multiValueQueryStringParameters: { a: ['1', '2'] },
}

The documentation on the API Gateway Event does not provide details on what the expected function of each of these is so I am looking for input as well as proposing one potential solution (this PR). Here are the options as I see it.

1. Have alpha create events where array values are exclusively in multiValueQueryStringParameters and non-array values are in queryStringParameters
2. Restore the old behavior of just using queryStringParameters even though that would seem to go against the spec
3. Update the logic in koa to not allow serverless-http to merge the keys that exist in both multiValueQueryStringParameters and queryStringParameters, i.e. prioritize params from multiValueQueryStringParameters
4. Something else?

The reason for this change is that patient-service is getting events that look like this

{
  queryStringParameters: {
    _tag: 'http://lifeomic.com/fhir/dataset|1234,http://lifeomic.com/fhir/source|LifeOmic%20Consent'
  },
  multiValueQueryStringParameters: {
    _tag: [
      'http://lifeomic.com/fhir/dataset|1234',
      'http://lifeomic.com/fhir/source|LifeOmic%20Consent'
    ]
  },
}

And when the params are parsed it has the following for ctx.query

{
  _tag: [
    'http://lifeomic.com/fhir/dataset|1234',
    'http://lifeomic.com/fhir/source|LifeOmic%20Consent', 
    'http://lifeomic.com/fhir/dataset|1234,http://lifeomic.com/fhir/source|LifeOmic%20Consent'
  ],
}

This causes the error because it has a tag filter with a , which is not allowed.

[shawnzhu]

Thank you! this is a great finding

[github-actions]

🎉 This PR is included in version 7.0.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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