Update types for Payment Method Configuration usage

[ryanmcdonald-stripe]

Summary & motivation

Update type definition for UPE now that we will allow passing a payment_method_configuration parameter.

Testing & documentation

Added validation invocation to test type addition.

[ryanmcdonald-stripe]

Waiting on official GA of the feature before merging

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ryanmcdonald-stripe]

Still waiting on formal GA before merging :)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ryanmcdonald-stripe]

Re-opening - Slow to GA the feature since we're still collecting feedback.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ryanmcdonald-stripe]

Re-opening, planning to merge this week on the cusp of GA launch.