tests: Extract routes module

[Turbo87]

to quote the doc comment:

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This module should contain all tests that test a single webserver route.

Each /api/v1 (or /api/private) sub-API should have its own module, with submodules divided by the specific endpoint (e.g. list, create, read, update, delete).

Examples

• testing all the ways authentication works or fails on a specific route
• testing error behavior of a route
• testing output serialization of a route
• testing query parameter combinations of a route

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note that not all tests have been migrated yet, but it's a start :)