Always use types over interfaces for basic object type definitions

[pmarsh-scottlogic]

Currently we are defining a lot of interfaces for plain objects.. It is more semantic to use simple object types.

At the moment we are disabling the eslint rule @typescript-eslint/consistent-type-definitions. We shoud change that so we are enforcing all type definitions to be types: @typescript-eslint/consistent-type-definitions': ['error', 'type'].

Acceptance criteria:

• eslint rule @typescript-eslint/consistent-type-definitions updated across frontend and backend
• no eslint errors
• no behaviour changes in the app