Fixed adding parameters for GraphQL APIs that already have parameters

[malincrist]

Problem

Adding parameters from the test console for GraphQL APIs that already have a parameter in the URL results in miss-formatted URLs with double '?' This problem occurs because our code checks for the '?' character only within the portion of the URL we create when adding query parameters.

Solution

Check for '?' throughout the entire URL, ensuring that we do not duplicate it.

Closes #2281

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