Generic Analytics Adapter

[bretg]

[from https://github.com//pull/3299]

We would like to define an analytics module that could work for multiple parties.

Use cases:

1. An analytics company wants to plug into many Prebid Servers and doesn't care about the JSON interface.
2. A publisher wants to get their own log-level data from their Prebid Server host company. We would need to be able to configure the module to log only for defined accounts and to a different endpoint for each. And not worry about GVLIDs in this scenario.

Requirements:

1. Configuration must be definable per account. e.g. call the generic analytics module for account 123 with endpoint A and no GVLID, but call it for account 456 to endpoint B and GVL 999.
2. The module should be able to write to HTTP or to a file. (should it support something like Kafka/Kinesis/Storm?)
3. The same account should be able to have multiple endpoints. e.g. they may want to put data in their own data warehouse as well as contract with a vendor.
4. PBS-Core needs to be able to handle the Purpose 7 analytics consent for each configuration entry.
5. It would be ideal if there could be a "basic" format and a "verbose" format if not a highly configurable JSON schema.