Way to easily check paid amount vs expected

[DarrenWestwood]

The expected_btc and paid_btc post meta has been removed. Merchants still want to easily check the amounts paid through Blockonomics.
We can add a new post_meta to display the blockonomics_payments_amounts, currently tracked in the paid_fiat db column.
The paid amounts can be displayed as a comma separated list to match the other blockonomics post_meta fields. eg.

OR

We can display the information in a single blockonomics_payments post meta in JSON format. This method allows us to display all the info relevant to an order in a structured manner. eg.