Allow Certain State structs to return constants if they always evaluate to a constant

[xiyler]

It could be worthwhile to look into make certain state creators (Most notably Map) return a constant if its 100% verified that it will always return that constant.

If we also applied the idea of #44 on state creators, we could potentially have something like this...

local IS_BAD = true

local result = Map(IS_BAD, {
   default = "This should be bad"
}) 

... to be optimized into something simple like this:

local is_BAD = true
local result = "This should be bad"

[xiyler]

This could also work on something like Derived if we can verify that its dependencies aren't dynamic (every Derived update doesn't change the dependency tree), and these dependencies are constants.

[xiyler]

Deferred to 0.5

[xiyler]

It's currently hard to evaluate whether an state object will always evaluate to constant considering dynamic dependencies are supported.