Hermes as the RNW Default Engine

[TatianaKapos]

Summary

React Native switched to Hermes as the default JavaScript Engine in .70, RNW should target .73 as our candidate to switch to Hermes. This tracks what currently needs to be accomplished before making the switch. Edit as needed with new issues.

Tasks

Beta Give feedback

1. Switch to an ABI-safe API
2. Profiler support
3. In-depth crash dump analysis
4. Resolve issues with promises
5. Add Intl API Support for Hermes JS Engine #87
   2 of 8
   enhancement +1
6. Update react-native-windows-init for hermes to be default for new apps
7. Decide how we want to handle upgrades for existing apps using chakra
8. Update app templates to assume hermes default
9. Reconcile codebase to expect hermes as the default (not UseHermes opt-in, but maybe UseChakra like UseV8)