Add further payment metadata for classification

[dechov]

Add more information to payment metadata, either in a single field or multiple, about how the payment originates: initial vs. renewal, UPE vs. non-UPE, shortcode vs. block, etc.

We already have payment_type but its value is "recurring" for all subscription-related payments, not just renewals. (There is also payment_context for WCPay subscriptions – see #3715 (comment)).

[jessy-p]

To come up with the list of fields, and after checking with architects, implement it.

[souravdebnath1986]

What are the use cases (+customers i.e. merchants, internal) for enhancing the payment meta eg: enhanced reporting.

[naman03malhotra]

Moving it back to "RFP" queue to discuss it during the prioritization call.

[aheckler]

Can we also add a bit of metadata to indicate the current version of WooPayments on the merchant site? This could be helpful for support during troubleshooting.