Core: support explicit ordering of model properties

[evanbb]

properties end up getting rendered in declaration order, but the order of iteration isnt guaranteed - fix this :)

[evanbb]

preferring to not add a property like order or priority or something to each model property configuration, i thought it would be good to change from an object

{
  prop1: prop1Config,
  prop2: prop2Config
}

to an ordered array of tuples

// if prop1 should render first:
[
  ['prop1', prop1Config],
  ['prop2', prop2Config],
]
// or, if prop2 should render first:
[
  ['prop2', prop2Config],
  ['prop1', prop1Config],
]

so long as all properties are specified exactly one, order should be up to developer.

building off this microsoft/TypeScript#13298 (comment) gave me a decent, very workable solution, but the code suggestions and error reporting leave a lot to be desired, and beyond 7 properties TS just gives up calculating thousands of permutations, stating Type instantiation is excessively deep and possibly infinite 💔 😭