Address S3994/S3995/S3996: Use Uri instead of string in parameters/returns/properties

[bart-vmware]

Address existing violations of the following, related rules:

• S3994: URI Parameters should not be strings
• S3995: URI return values should not be strings
• S3996: URI properties should not be strings

in the codebase and set severity to Warning in Steeltoe.Debug.ruleset and Steeltoe.Release.ruleset.

To find existing violations, enable the rule (see above) and rebuild src/Steeltoe.All.sln to make them appear in the Output window.

To address the violations, choose from the following on a case-by-case basis:

• Fix the violation by changing the code to not violate the rule
  • When the method calls into a .NET method that has an overload for Uri, call that instead and update the method signature to take a Uri instead of a string. Consider adding an overload that takes a string, which calls this method
• Suppress the violation in code using #pragma warning disable/restore, preceded by a justification comment if not obvious

Note: This issue mitigates security risks, though it requires a more thorough investigation on the best path forward. Should we enable (some of) the rules, or are there too many false positives, leading to numerous suppressions?

[bart-vmware]

Many violations (see the list at https://github.com/SteeltoeOSS/Steeltoe/pull/1053#issuecomment-1332214236) originate from Connectors, which allow a comma-separated URI format that's incompatible with System.Uri. It's unclear to me whether we need to preserve support for that format.