Prebid Targeting: add a configurable "bidCacheFilterFunction" (#7993)

[harpere]

cherry-picked the change from PR #7993 to this 5.20.x-legacy branch.

• add a configurable "bidCacheFilterFunction" to determine whether to use a cached bid

• tiny != changed to !==

Co-authored-by: Eric Harper eharper@rubiconproject.com

Type of change

• Bugfix
• Feature
• New bidder adapter
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Does this change affect user-facing APIs or examples documented on http://prebid.org?
• Other

Description of change

• test parameters for validating bids

{
  bidder: '<bidder name>',
  params: {
    // ...
  }
}

• contact email of the adapter’s maintainer
• official adapter submission

For any changes that affect user-facing APIs or example code documented on http://prebid.org, please provide:

• A link to a PR on the docs repo at https://github.com/prebid/prebid.github.io/

Other information