Support multiple instances of query param

[LucasPickering]

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You should be able to specify query params multiple times.

Describe the solution you'd like
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query should be able to take a list[string] in addition to the map[string, string], where each string is a key=value format (similar to docker-compose's environment mapping). This would allow you to specify a query param multiple times. When constructing the URL, the repeated param would simply be repeated.

recipes:
  repeated: !request
    url: "{{host}}/get_data"
    query:
      - a=1
      - b=1
      - a=2

This would render to this URL: <host>/get_data?a=1&b=1&a=1

Describe alternatives you've considered
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Simply allowing duplicate keys. This doesn't work because the YAML spec requires keys to be unique.

Additional context
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Maintaining mapping[string, string] support is important for backward compatibility