Send `link_type` FPTI Tag

[jaxdesmarais]

Summary of changes

• Send link_type in batch_params to PayPal's analytics service (FPTI) - this will help us determine if users are going through the universal link or deeplink flow
• Verified via FPTI explorer we are sending this new tag as expected
• Updated UnitTests

Notes for Android

• In Android v4 we send venmo.app-links.<STATUS> events - these are noted in a new tab on the FPTI Events excel sheet
• Ticket DTBTSDK-3596 covers the Android v5 workstream for adding this param

Checklist

• [x] Added a changelog entry

Authors

• @jaxdesmarais