[ENG-4961] make Boa configurable via API v2

[Johnetordoff]

Purpose

Allow users to configure their account details entirely via the V2 api.

Changes

• override the serializer to allow credentials to be updated
• add tests

QA Notes

Please make verification statements inspired by your code and what your code touches.

• Verify
• Verify

What are the areas of risk?

Any concerns/considerations/questions that development raised?

Documentation

Side Effects

Ticket

https://openscience.atlassian.net/browse/ENG-4961