Support Refunds and fix Dispute schema for evidence column

[ilkkapeltola]

Description of change

This PR does two things:

• Adds working support for Refunds, which for some reason has so far not been included in the tap
• Fixes the schema for disputes.evidence. In the current form, the elt fails with the snowflake target (pipelinewise variant) due to the wrong schema

Manual QA steps

• run the ELT

Risks

• Others using the tap might have done other custom fixes for the dispute column. It doesn't fail on all rows, just some.

Rollback steps

• revert this branch

[syahdeini]

Tested and works well!