fix js identifiers containing dashes

[4rthem]

Q	A
Branch?	main
Tickets
License	MIT
Doc PR

With the following entity:

resources:
  App\Entity\FooBar:
    shortName: foo-bar

typescript template outputs invalid JS:

type foo-bar {
   // ...
}

The following PR replaces dashes to underscores to produce valid JS code.

[alanpoulain]

Thanks for this PR.
I've made a little change: when the field name is an invalid identifier, it will be quoted instead.