test(Integration): add contexts related tests

[blizzz]

This PR includes some foundations for Context integration tests and a couple of create and read scenarios, plus some smaller fixes.

Let's got with this and add more scenarios in follow-ups. I'll open an overview issue.

Scenarios covered

Creation

• [x] Create context with views and tables
• [x] Create context with inaccessible table
• [x] Create context with inaccessible view

Reading

• [x] Read all contexts
• [x] Read specific owned context
• [x] Read inaccessible context
• [x] Read a non-existing context

Small bug fixes included

• ensure that node parameters are treated as integer values
• report node permissions on creation
• normalization of page result format
• atomic handling of DB inserts on create + error handling + openapi update

[blizzz]

/backport to stable0.7

[blizzz]

Nice to isolate the stored results with the collection manager 👍

Thx! In a distant follow up I want to move the tables and views there as well and have the FeatureContext less cluttered :)