add openAQ and/or IQAir compatability

[zzkt]

datasources

...add the option to use the openAQ API and/or IQAir and/or other datasources.

OpenAQ

OpenAQ provides a REST API (reference) for programmatic access to the OpenAQ database. There are 2 versions (as of JUL 2023)

• version 1 - only includes reference/government sources, i.e. does not include low-cost sensors
• version 2 - includes full OpenAQ dataset and additional query features compared to version 1

"Starting July 1 2023 an API Key will be required to access the OpenAQ API at the current rate limit. Key-less access will still be available but at a significantly lower rate limit."

IQAir

IQAir requires an AirVisual account and an API key