feature: enforce named parameters for mf6 component types

[wpbonelli]

Is your feature request related to a problem? Please describe.
Classes accepting long lists of parameters (e.g. mf6 simulations, models and packages) should not be initialized with anonymous (ordered) arguments since it is unclear which corresponds to which parameter.

Describe the solution you'd like
Consider using a * in the signature to prohibit ordered argument-passing.

Additional context
Suggested by @deltamarnix