[Feature] [Datepicker] Open on Year or Month view

[c00]

Is your feature request related to a problem? Please describe.

Use cases: Selecting Date of Birth, Date of document issuance, date of entry, or any other date that is likely not to be this year/month (and where year/month aren't predictable).

Let's go with DOB for the rest of this FR.

Currently a user will open the dialog, and either click the back button a lot, or click the year (if they realize they can) and find the required year, month and day.

Describe the solution you'd like

Add an option in the config like openView with possible values year, month, day. It would default to day, as that is the current behavior.

When the datepicker dialog opens, the initial view should go to the configured view (year in the example) as a starting point, rather than always defaulting to day.

The new flow would be:

1. User opens dialog
2. Selects year
3. Selects month
4. Selects day.

Describe alternatives you've considered

I've looked at the current DatePicker directive to see if this could be achieved relatively easy through some manual triggering, but it can't.

Alternatives would be to take a view argument in toggle and open and respond with the needed starting view.

Additional context

Note that this is different form minDate. minDate limits the view. This feature would only provide a starting point, but still have the months, years and day selection available.

[fhuschle]

I would like to do that