Add ACCEPT_TERMS_OF_SERVICE event in StripeTerminalProvider

[tim-lin-bbpos]

Summary

Add ACCEPT_TERMS_OF_SERVICE event in StripeTerminalProvider

Motivation

To align existing design, we'll add ACCEPT_TERMS_OF_SERVICE to StripeTerminalProvider as well.

Testing

• [x] I tested this manually
• [ ] I added automated tests

Documentation

Select one:

• [ ] I have added relevant documentation for my changes.
• [x] This PR does not result in any developer-facing changes.