Adding support for CAMT.053 XML data imports

[aodhan-domhnaill]

Motivation

CAML.053 is often given out by EU based banks https://www.sepaforcorporates.com/swift-for-corporates/a-practical-guide-to-the-bank-statement-camt-053-format/

It offers more drop-in parsing than CSV, especially with different languages

Changes

I made the following changes

• Refactoring the import to allow other import formats
• Reused section of the code from before (ignore whitespace diff for cleaner diff)
• CSV logic should be unchanged, just some chunks moved into reusable functions
• Added a small bit of testing (happy to add more)

[howeyc]

I like it. Thanks.