test(amazonq): add tests for edge cases

[Hweinstock]

Problem

There are two edge cases discovered during testing that warrant some tests.

1. the language server will respond without a range, causing the result to not be rendered.
2. the language server COULD respond with a StringValue instead of string (currently doesn't, but valid in the type contract).

Solution

• add tests for these cases, and do minor refactoring to make this easier.

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• Treat all work as PUBLIC. Private feature/x branches will not be squash-merged at release time.
• Your code changes must meet the guidelines in CONTRIBUTING.md.
• License: I confirm that my contribution is made under the terms of the Apache 2.0 license.

[Hweinstock]

In non-testing scenarios, editor.selection.active appears to always be the same as the position passed in here.