Rename Bicep.Core.Samples -> Bicep.Core.TestScenarios or something

... so people don't think these are still intended to be recommended usage (they used to be but are now only used for tests)

The issue does not name any files or tests; start by searching the repository for references to Bicep.Core.Samples and identify the test-only projects that use it. Done means an agreed replacement name is applied consistently without changing test behavior, with the relevant test suite still passing.

Written by the indexing model from the issue text.