fix: Reject ambiguous parameters in `ContinueBasic::new`.

[coveralls]

Pull Request Test Coverage Report for Build 5465556943

• 4 of 5 (80.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.006%) to 93.254%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
imap-types/src/response.rs	4	5	80.0%
<!--	Total:	4	5	80.0%	-->

Totals
Change from base Build 5465413208:	-0.006%
Covered Lines:	9123
Relevant Lines:	9783

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💛 - Coveralls