Move solo machine client state initialize logic into client module implementation

[colin-axner]

Summary

Once #5806 is merged to main, it makes sense to move over the solo machine client state Initialize implementation into the light client module implementation as it is quite basic. It asserts that the provided consensus state matches the consensus state in the client state state and the sets the client state to store

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[DimitrisJim]

Worth pointing out that multiple of solomachine's impls can be folded into the light client functions now.

In addition to that, we can also very easily make all these previously exported functions private (Assumption would be API is now defined on the light client module interface and the now trimmed down ClientState one)