Feature request: mandatory fields

[Frenggi]

Is your feature request related to a problem? Please describe.
For the form fields (date picker, select, text area, text field, time field) we designed a mandatory state. This is currently missing in the Angular component implementation.

Describe the solution you'd like
The mandatory state should be added to the components like it is designed on digital.sbb.ch.

Describe alternatives you've considered
For consumers, an alternative is to use only validation messages. But it should be supported both, because it's depending on complexity of an application which is the better variant.

[mhaertwig]

@mcilurzo previously, lean mandatory fields had a yellow background. This is no longer the case in figma. Should we address this or leave it as it is?