integrate HardwareNamePrefix, HardwareNameVersion into 51Degrees DD Module

[justadreamer]

Motivation

Provide more precise and more expected signal to the SSPs/DSPs in an attempt to optimize for publisher revenue.

Background

Currently the module does not fill the ortb2.device.hwv field because there was no direct mapping to these field provided by 51Degrees under OpenRTB mappings - it only "said that this information is contained under HardwareModel property". However with the addition of HardwareNameVersion property we can fill this value.

We were also using populating ortb2.device.model as HardwareModel if we had it - including both Prefix and Version into the model. With the fallback to HardwareName (coma-concatenated) if there was no value returned for HardwareModel. This led to device.model potentially being over-specific (specifying full device name and version while the SSP/DSP expected just "iPhone" not "iPhone 12 Pro Max" - this is a hypothesis however).

Objective

Change the logic like so:

1. If HardwareNamePrefix is non-empty use it to populate device.model, otherwise fallback to the existing code.
2. Populate device.hwv with HardwareNameVersion.
3. Add unit tests.
4. Update documentation in the prebid.github.io repo.
   cc: @51Degrees/data please review - if you are happy with this we'll move on with the implementation.