Globalize-runtime cannot have two unit formatters with same options but different number formatters

[mattyork]

Globalize version: 1.2.3
Globalize compiler version: v0.2.4

Example code (might not compile, but hopefully illustrates the point):

// compilation time - note that the only difference in formatters is the number formatter options
const unitFormatOptions1 = { numberFormatter: globalizeInstance.numberFormatter({minimumIntegerDigits: 1}) };
const unitFormatOptions2 = { numberFormatter: globalizeInstance.numberFormatter({minimumIntegerDigits: 2}) };
compileFormatters([
  globalizeInstance.unitFormatter('hour', unitFormatOptions1),
  globalizeInstance.unitFormatter('hour', unitFormatOptions2)
]);


// ... now to the runtime
const x = globalizeInstance.formatUnit(3, 'hour', unitFormatOptions1); 
const y = globalizeInstance.formatUnit(3, 'hour', unitFormatOptions2);

Expected: x == "3" and y== "03"
Actual: x == "3" and y == "3"

The problem is that the unit formatter takes a number formatter (a function) as one of its options, but the runtime keys are generated by JSON.stringifying the options (see here), and JSON.stringify stringifies functions as empty string.

So, the runtime key is resolved to the same thing in both formatters, even though they have different number formatters.

[mattyork]

#705 is related and may have the same solution