fix(ionic-angular): Add support for environment feature

[fleboulch]

Ionic-app-scripts introduced environment feature in v3.2.0.

Need to add types property in compilerOptions to be able to use the environment feature (as explained here: ionic-team/ionic-cli#3541)

[imhoffd]

@florentl I'm not sure we want to put "types": [] in the starters by default, because it deviates from the default behavior of TypeScript in a way that may be unclear to those that aren't aware of it.

If anyone installs a library and then adds that library's typings (e.g. npm i -D @types/lodash), the types won't be used by TypeScript and there will be no discernible way why. But if "types": [] is added manually by them, they'll know why the behavior changed.

[imhoffd]

I think this should be fixed via documentation instead of providing the process declaration by default.

[fleboulch]

I understand your point.
I was trying to update an ionic community starter and the travis tests failed because I introduced the environment feature. I will see what can be done to fix them.

Thanks

[imhoffd]

Sounds good. 👍

Closing this, but thank you for the PR.