Add rule that protocol composition type aliases should be sorted alphabetically

[calda]

Summary

This PR proposes a new rule that protocol composition type aliases should be sorted alphabetically.

Autocorrect is implemented in the SwiftFormat sortTypealiases rule, added in nicklockwood/SwiftFormat#1445.

// WRONG (not sorted)
public typealias Dependencies
  = UniverseBuilderProviding
  & LawsOfPhysicsProviding
  & UniverseSimulatorServiceProviding
  & PlanetBuilderProviding
  & CivilizationServiceProviding

// RIGHT
public typealias Dependencies
  = CivilizationServiceProviding
  & LawsOfPhysicsProviding
  & PlanetBuilderProviding
  & UniverseBuilderProviding
  & UniverseSimulatorServiceProviding

Reasoning

Type aliases are an unordered list with no natural ordering. Sorting alphabetically keeps these lists more organized, which is especially valuable for long protocol compositions.

Please react with 👍/👎 if you agree or disagree with this proposal.

[erichoracek]

Good stuff!