Add a gcp project picker to the repo flow

[siggisim]

Screenshot:

[bduffany]

I think you can simplify this by having the Picker render inline rather than in a modal, and then instead using <Modal> from app/components/modal/modal.tsx

<Modal
  isVisible={this.state.isPickerVisible}
  onRequestClose={() => this.setState({ isPickerVisible: false })} >
    <Picker
      options={this.state.pickerOptions}
      onSelect={selection => { this.setState({ selection, isPickerVisible: false}); } /> 
</Modal>

Benefits:

• Can get rid of the custom CSS for showing the backdrop behind the picker (Modal should already handle this)
• Inherit other nice behaviors from <Modal> such as dismissing with Esc
• Picker becomes more generally useful, e.g. we might have a form where it makes sense to render this inline in the form
• No need for the global picker service which adds a bit of complexity / indirection
• No need to render <Picker> in the root component

[bduffany]

nit: the stuff under app/components doesn't use the "Component" suffix

[siggisim]

Done

[siggisim]

I think you can simplify this by having the Picker render inline rather than in a modal, and then instead using <Modal> from app/components/modal/modal.tsx

<Modal
  isVisible={this.state.isPickerVisible}
  onRequestClose={() => this.setState({ isPickerVisible: false })} >
    <Picker
      options={this.state.pickerOptions}
      onSelect={selection => { this.setState({ selection, isPickerVisible: false}); } /> 
</Modal>

Benefits:

• Can get rid of the custom CSS for showing the backdrop behind the picker (Modal should already handle this)
• Inherit other nice behaviors from <Modal> such as dismissing with Esc
• Picker becomes more generally useful, e.g. we might have a form where it makes sense to render this inline in the form
• No need for the global picker service which adds a bit of complexity / indirection
• No need to render <Picker> in the root component

I've moved the Picker component to use a Modal instead of creating its own shade. That gets rid of the custom CSS and the nice modal behaviors like support for Esc (though I feel the focus behavior is a bit wonky - i.e. if you click on the shade when you've got another component focused, it doesn't seem to close the modal - it requires another click on the shade).

I like having the picker service, because it allows you to just say "have the user pick one of these options and give me the result in a promise" rather than having to build a whole fancy dom structure and manage state any time you want the user to pick something. Kind of like the old let result = input("Enter your input") api but a bit nicer. I'm down to separate this out into more reusable components once we have the need for more customization / reuse in other places.