Add appLinkReturnUri to BraintreeClient

[tdchow]

Summary of changes

• Add appLinkReturnUri as a parameter passed to the BraintreeClient constructor
• Remove unused BraintreeClient constructors that were marked as internal but only used in test classes
• Collapse public BraintreeClient constructors by using default values and @JvmOverloads annotation

Checklist

• [x] Added a changelog entry
• [x] Relevant test coverage

Authors

List GitHub usernames for everyone who contributed to this pull request.

[sarahkoop]

Let's also add the ongoing CHANGELOG entry for the BraintreeClient changes (unless you want to do all CHANGELOG at the end)

[tdchow]

Let's also add the ongoing CHANGELOG entry for the BraintreeClient changes (unless you want to do all CHANGELOG at the end)

Good catch! I completely forgot about the changelog. Making the update now.