There are too many (hex) assembly-specific tools in App

[john-science]

It has been noted that the default ARMI App() actually has a lot of hex-assembly or even SFR assumptions in it.

Well, after we make some new Core subclasses for HexAssemblyCore or SFRCore or what-have-you, there is an easy method to point at a specific Core type in an ARMI Application:

armi/armi/reactor/__init__.py

Lines 75 to 81 in 0e830d2

	def defineSystemBuilders() -> Dict[str, Callable[[str], Union["Core", "ExcoreStructure", "SpentFuelPool"]]]:
	from armi.reactor.excoreStructure import ExcoreStructure
	from armi.reactor.reactors import Core
	from armi.reactor.spentFuelPool import SpentFuelPool
	return {
	"core": Core,

This would also be a great time to look at the default Plugins and Interfaces in the default ARMI App to decide which should stay with the default App and which should move to the new SFRHexApp or whatever:

armi/armi/apps.py

Lines 90 to 97 in 0e830d2

	cli.EntryPointsPlugin,
	bookkeeping.BookkeepingPlugin,
	fuelCycle.FuelHandlerPlugin,
	fuelPerformance.FuelPerformancePlugin,
	neutronics.NeutronicsPlugin,
	safety.SafetyPlugin,
	thermalHydraulics.ThermalHydraulicsPlugin,
	reactor.ReactorPlugin,

NOTE: This change would require some docs updates. We will need to document the change, of course. But also, this will break the current Settings and Parameters reports.

[john-science]

This ticket came out of a conversation with @albeanth , @alexhjames , @drewj-tp , @keckler , and @opotowsky .

[drewj-tp]

Core-specific variant / sibling ticket - #1448