Make GreenNode.CreateList static

[HurricanKai]

As discussed with @CyrusNajmabadi on discord this PR makes GreenNode.CreateList static and adjusts all usages.

This done to simplify the method and remove the virtual call which should help performance somewhat, but I couldn't get perf numbers that could directly confirm this.

I'm not sure whether members should also be reordered. I left them as is for now.

[Dotnet-GitSync-Bot]

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[dnfadmin]

All CLA requirements met.

[333fred]

Done review pass (commit 1)

[CyrusNajmabadi]

@dotnet/roslyn-compiler can we get a second pair of eyes on this nice community PR? :)

[333fred]

LGTM (commit 4). @dotnet/roslyn-compiler for a second review. There are no perf numbers in this PR, but Kai is planning on submitting a second PR that actually refactors the implementation of GreenNode.CreateList that removes a bunch of double-allocations that should have a big impact, and this first change will simplify that.

[CyrusNajmabadi]

There are no perf numbers in this PR,

True. Though changing these virtual methods (and extra parameters and whatnot) to just static calls, should be pure benefit. At worse, we should have no perf change. A best, potentially some uptick :)

[333fred]

Thanks @HurricanKai!