MSDKANDRD-1895 Fixed stage pipeline release apk transaction failure issue
Fixes:
- Fixed transaction failure issue associated with stage pipeline generated artefacts.
- Modified SSL certificate validation to act based on the gateway server(To match with same behavior as IOS SDK).
- Modified TrustPaymentsApiService class to use lamda functions.
- Upgraded Retrofit version of SDK and downgraded Okhttp dependency to be compatible with Retrofit version.