Bring all ScalarBigXXXStore methods into consistency with the types defined in the stores package

[erights]

The MapStore and SetStore addAll methods are correctly typed and implemented by @agoric/store. But it lacks both explanation and tests.

The virtual and durable MapStores fail to implement addAll at all. The virtual and durable SetStores implementations of addAll are incomplete: they correctly recognize and process an Iterable argument. But they do not recognize a CopySet argument.

[erights]

Also snapshot methods such as

agoric-sdk/packages/store/src/stores/scalarMapStore.js

Lines 100 to 101 in 09b993a

	snapshot: (keyPatt = undefined, valuePatt = undefined) =>
	makeCopyMap(entries(keyPatt, valuePatt)),

are implemented only by heap stores, but not by virtual or durable ones. These are the dual of the addAll methods, so it makes sense that they were omitted together.

[FUDCo]

The virtual and durable SetStores implementations of addAll are incomplete: they correctly recognize and process an Iterable argument. But they do not recognize a CopySet argument.

I don't understand what this means. Are CopySets not iterable?

[FUDCo]

As I was working through how to apply the fixes for this, I discovered another error: it appears we have an internal-only operation on sets (addToSet) being added to the public API of all the collection classes. This seems to be the consequence of some unrelated cleanup. This was introduced in commit c81d367 (I poked around in the git log to see what idiot had done this and of course it was me). If @erights concurs I'd like to recast this issue as "Bring all ScalarBigXXXStore methods into consistency with the types defined in the stores package".

[erights]

If @erights concurs

Concur!

[erights]

I don't understand what this means. Are CopySets not iterable?

Please read endojs/endo#1583 ! Important (but very non urgent)