adUnit?.pbAdSlot creates "adSlot" key and not pbAdSlot.

[rBeefrz]

Describe the bug
adUnit?.pbAdSlot defines 'adslot' and not 'pbadslot'.

To Reproduce
Steps to reproduce the behavior:

1. Prebid-mobile-android-master
2. Modify one of the gam original activities (say GamOriginalApiDisplayBanner300x250) and add:

   adUnit?.gpid = "/21808260008/prebid_demo_app_original_api_banner_300x250_order"
   adUnit?.pbAdSlot = "/21808260008/prebid_demo_app_original_api_banner_300x250_order"

3. Run PrebidDemoKotlin & retrieve the request for the 300x250 banner.

Expected behavior
Unless i'm very much mistaken we expect pbAdSlot to define pbadslot in the imp[].ext and not 'adslot', as per here.

Screenshots

Additional context
Add any other context about the problem here.

[YuriyVelichkoPI]

@OlenaPostindustria please, check the iOS behaviour.

[OlenaPostindustria]

@YuriyVelichkoPI, iOS SDK creates adslot key as well.

[YuriyVelichkoPI]

@OlenaPostindustria @ValentinPostindustria let's fix it in following way

If the publisher uses property pbAdSlot - add the imp[].ext.data.pbadslot field to the request.

Don't remove the current adslot field from the request. Add warning log message: "Prebid SDK will stop sending imp[].ext.data.adslot" field soon. If you still need it, add a comment to: #810."