Increase robustness of Ihat URL bootstrapping

[ci skip]
- When request is not JSON, reject it and log a warning
- Only assign ihat_supported_formats if it can be parsed as JSON
Merge pull request #535 from Tahi-project/fix-ihat-url-initialization

Increase robustness of ihat url bootstrapping
Merge branch 'master' into supporting_info_route
ensure that the env config is not mutated after test
ihat default format should be parseable
Merge pull request #536 from Tahi-project/restore_env_after_test

Ensure that the env config is not mutated after test
Fix expectation to represent correct behavior
Merge branch 'master' of github.com:Tahi-project/tahi
Merge branch 'master' into supporting_info_route