test(server/graphql): assert error code and fix some tests

[iainsproat]

Description & motivation

In tests the code of error needs to be asserted, not just the presence of an error. It was possible for tests to pass but due to an unexpected error code. This PR introduces assertions on error codes to prevent this type of regression.

Changes:

• assertions on the error code in graphql tests
• when deleting a Speckle app, if the app cannot be found we return a Forbidden Error.
• A user input error is returned in the case where a token cannot be removed. Either the token does not exist or the user does not own it.
• some tests polluted the test environment through re-use of the same email address for the test user. A random email address is used to prevent test pollution.
• fixes invalid graphql in a test

To-do before merge:

Screenshots:

Validation of changes:

Checklist:

• My pull request follows the guidelines in the Contributing guide?
• My pull request does not duplicate any other open Pull Requests for the same update/change?
• My commits are related to the pull request and do not amend unrelated code or documentation.
• My code follows a similar style to existing code.
• I have added appropriate tests.
• I have updated or added relevant documentation.

References