fix: fixing "500 internal server error" response

[artursudnik]

This PR implements a logic that makes VpSubmissionVerifierService.verifyVpRequestSubmission return an error item instead of throwing an exception resulting in a "500 internal server error" HTTP response.

[jrhender]

Maybe it's better to initialize the empty array and use const

Suggested change

	let partialErrors;
	const partialErrors = [];

[artursudnik]

AFAIR it forced next lines to be split into more steps as { errors: partialErrors } = pex.evaluatePresentation( is not valid then. And it would require this that is less readable I think:

const { errors } = pex.evaluatePresentation(
          presentationDefinition,
          presentation as IPresentation
        )
        
        partialErrors.push(...errors);