[Woo POS] Add Onboarding Flow Support in POS Mode

[AnirudhBhat]

We need to implement proper onboarding flow support in POS mode, which was previously skipped for the POC. The lack of onboarding flows has resulted in merchants with the StripePendingRequirement error being unable to use POS, even though they are eligible. This task will involve integrating the necessary onboarding steps to ensure all eligible merchants can use POS.

Tasks:

1. Implement onboarding flow in POS mode.
2. Ensure that merchants with pending requirements can complete the onboarding process.

[dangermattic]

Thanks for reporting! 👍