Add tests for strict validation in combination with api key in query

[Ruwann]

Continues on the work of #1077 by moving the test fixtures into the secure_endpoint fixture and adding a test for it in test_secure_api.py.

The test will check whether an api key in the query will not lead to an error when strict_validation is enabled.

[coveralls]

Pull Request Test Coverage Report for Build 4647463240

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 93.887%

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Totals
Change from base Build 4646044651:	0.03%
Covered Lines:	3333
Relevant Lines:	3550

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💛 - Coveralls

[RobbeSneyders]

Nice, glad to see some things move out of the simple app :)

Was this fixture just not used before?

[Ruwann]

Exactly, almost everything was there (fixture, swagger, view function) except an actual test and app with strict_validation enabled