[Date Range Picker, Date Picker] Discrepancies in the calendar-related customization options- align with WC

[ddaribo]

The IgxDateRangePicker does not expose any means of customizing the calendar. Additionally, it is always displayed with no header.

1. In WC IgcDateRangePicker, and in the Angular IgxDatePicker, in dialog mode, the calendar is displayed with a header by default. The IgxDateRangePicker is always displayed without header.
2. In WC IgcDateRangePicker exposes the ability to customize the calendar through these props and these about disabled & special dates also.
   The below table compares the different options:

WC DP & DRP	Angular DatePicker	Angular DateRangePicker	Description
headerOrientation	headerOrientation	-	Specifies the orientation of the calendar header - applicable in dialog mode
orientation	-	-	Specifies the orientation of the days views in the calendar
hideHeader	the igxCalendarHeader template is exposed, however, leaving it empty does not hide the header -> no means to achieve this	-	Hides the header - applicable in dialog mode
slot[name='title']	the igxCalendarHeaderTitle template content targets this	-	Replaces the default current date/range text in the calendar header. Applicable only in dialog mode.
slot[name='header-date']	the igxCalendarHeader template content targets this	-	Replaces the calendar header content. Applicable only in dialog mode.
-	the igxCalendarSubheader template	-	Renders a subheader text in the calendar; By default this is the area, where months and years navigation buttons are placed
visibleMonths	displayMonthsCount	displayMonthsCount	Sets the number of months in the calendar picker. However the WC one is clamped to at most two, while in Angular >2 are allowed
activeDate	-	-	Sets the activeDate of the calendar
disabledDates	disabledDates	-	Sets disabled dates in the calendar
specialDates	specialDates	-	Sets special dates in the calendar
weekstart	weekStart	weekStart	self-decriptive
showWeekNumbers	showWeekNumbers	showWeekNumbers	self-decriptive
hideOutsideDays	hideOutsideDays	hideOutsideDays	self-decriptive
keepOpenOnOutsideClick	overlaySettings: keepOpenOnOutsideClick	overlaySettings: keepOpenOnOutsideClick	self-decriptive
keepOpenOnSelect	-	-	In Angular, these type of props are related to the overlay service, so nothing to be done there for the moment

The currently exposed calendar templates for the IgxDatePicker (note: they are currently not part of the IGX_DATE_PICKER_DIRECTIVES and have to be additionally imported - IgxCalendarHeaderTemplateDirective, IgxCalendarSubheaderTemplateDirective ?):