Consolidate type checking between params and prototypes

[jessicayuen]

Currently there exists two areas of parameter type checking in cmd/prototype.go and metadata/params/params.go. Since these are operating on the same parameters, we should consolidate this discrepancy.

[jessicayuen]

Hmm so I want to say that this might not be possible for the following reason:

The prototype schema has clearly defined parameter types, that the prototype writer can specify. Ex: String, NumberOrString.

The component params are inferred based on the command line input or the literals in the .jsonnet param files.

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The solution I see around this is 1) removing clearly defined types from prototypes 2) adding clearly defined types to component params.

Neither I think are feasible due to the nature of how these params are provided in each context. Thoughts @hausdorff?