Use Adzerk "e-dash" domains

[karnowski]

Background

For operational, performance, and data privacy concerns, Adzerk has migrated customers from the old default Decision and UserDB APIs hostname, engine.adzerk.net, onto individual URLs based on their network ID.

The new "e-dash" style URLs look like:
e-[networkid].adzerk.net

For example, the demo network, 23, uses the URL: e-23.adzerk.net

Acceptance Criteria

• The SDK no longer uses the engine.adzerk.net default.
• The default URL's hostname is now based on a top-level network ID passed in during initialization.
• The default hostname follows the "e-dash" pattern: e-[networkid].adzerk.net
• An integrating developer can explicitly override the hostname. In this case the "e-dash" hostname is ignored.

Tech Notes

Note that you can still set a network ID on the individual placements, although in practice no one really does this. If they do, however, then the top-level request still needs to go to one and only one "e-dash" domain host. So we'll need to add a top-level network ID that determines the host. The new Decision SDKs (Java, JavaScript, Ruby, Python) also use that top-level on the placement level if it's not explicitly set. It'd be nice to follow that approach here as well, but it is not strictly required.

There's already a top-level networkId, but it appears optional? We'll need to make it non-optional. If this requires a breaking change that is okay. It'll just need to be documented

[karnowski]

Also, I'm assuming that no cookies or other "local storage" will be disrupted by this URL change, right?

[subdigital]

Also, I'm assuming that no cookies or other "local storage" will be disrupted by this URL change, right?

Correct