Cherrypick: Define the calculateRankingScore method and Key.

Define the key to be used to store the rankingScoreOffset inside the
ScoredNetwork bundle. Implement a platform API method to calculate the
ranking score for a given rssi.

OCL: ag/1688711

Bug: 33049302
Test: Unit tests
Change-Id: Ia3fea2197d7c211a2313fced8713d79d8d5f4f6e
Merged-In: Ia3fea2197d7c211a2313fced8713d79d8d5f4f6e
Topic: ScoredNetworkRankingScore