Add type system tests for SettingsDefinition

[dskloetc]

Description

The config system defines some intricate types that enforce certain characteristics on the settings derived from the definition. Things like "if a setting of type 'number' has a default value, that default value must be a number or "only settings of type 'enum' can have options.

I'm looking into extending the config system to support variable variables where the actual variable name depends on a parameter such as network.

In the process, I'll be changing the types and I want to make sure I don't break the existing restriction imposed by the type system.

Change

Add a file with "type system tests". These are type declarations that either must be accepted or rejected by the compiler. The ones that must be rejected are annotated with @ts-expect-error. This will cause the compiler to produce an error if the type declaration ever becomes valid.

Testing

1. Run yarn test.
2. I've manually changed some of the test to check that they fail in the expected way.

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NPM Publishing labels 🏷️

🔵 This PR has the none label set and it will not cause a version bump.

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❌ failed to create version bump PR
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