Added a login pushed authorization request to allow third parties to pass profile hint

[lalwani]

This PR adds the functionality to submit profile values to Uber backend and pre-populate the results during auth. For example, supplying phone number would have the phone number field filled when launching the signup flow. Note, this only works for implicit and auth code login types, not native. OAuth 2.0 PAR Rfc https://datatracker.ietf.org/doc/html/rfc9126

The changes include:

• A new ProfileHint type to specify email, phone number, and name
• A new builder method added to SessionConfigutation to allow supplying ProfileHint
• A new endpoint par used to submit values to BE and get a request_uri in response
• Added callback to pass request_uri back to the caller
• Changing login.uber.com -> auth.uber.com
• Unit tests
• bump up java version to 1.8
• upgrade gradle to 4.8

[lalwani]

abandoning in favor of https://github.com/uber/rides-java-sdk/pull/49