chore: `static_assert` error message fix and split into is-dynamic and is-false

[michaeljklein]

Description

Fix static_assert error message

Problem*

Error message for static_assert was ~"Argument to static_assert is false or dynamic" at some point, but currently is copy/pasted from the nested slices error

Summary*

Additional Context

Documentation*

Check one:

• [x] No documentation needed.
• [ ] Documentation included in this PR.
• [ ] [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• [x] I have tested the changes locally.
• [x] I have formatted the changes with Prettier and/or cargo fmt on default settings.

[TomAFrench]

Seems like we should be able to determine which case we've encountered. It would be nice to for devs to be able to tell if they have a false or just undecidable assertion.

[michaeljklein]

@TomAFrench sure, can add that 👍