feat(cli): transform based on engine

[EvanBacon]

Why

• Reduce the amount of Babel transformations based on the jsEngine for a particular platform.
• Hermes supports more modern language features than the default React Native target, so we don't have to transpile as much. This is an unstable feature that seems reasonable enough to turn on by default.
• Users can overwrite the default by using the same unstable_transformProfile as before.
• Web will also use this newer transform as the majority of modern browsers support more features than Hermes.

The following will now be disabled when using Hermes:

@babel/plugin-transform-computed-properties
@babel/plugin-transform-parameters
@babel/plugin-transform-shorthand-properties
@babel/plugin-proposal-optional-catch-binding
@babel/plugin-transform-function-name
@babel/plugin-transform-literals
@babel/plugin-proposal-numeric-separator
@babel/plugin-transform-sticky-regex
@babel/plugin-transform-spread
@babel/plugin-proposal-object-rest-spread
@babel/plugin-proposal-optional-chaining
@babel/plugin-proposal-nullish-coalescing-operator
@babel/plugin-transform-runtime -> regenerator

And @babel/plugin-transform-named-capturing-groups-regex will be enabled.

Expressed as a diff:

How

• Add an engine flag to the URL to trigger a cache invalidation per-platform if the app.json settings change.
• Pass the flag to babel where we can toggle on Hermes mode.

Test Plan

• Tested in sandbox, also wrote unit tests for the syntax.