targets: https://github.com/telerik/kendo-themes-private/issues/246

This PR targets the following items from the related issue:

Toolbar

• see if Angular-specific toolbar specs/templates can be removed.

Map

• k-button-square is missing on navigator buttons
  It seems that the class is obsolete - can we remove it?

Expansion panel / Expander

• should use k-hidden instead of k-d-none when not expanded

Switch

• add offLabel and onLabel in the switch templates

TabStrip

• check if we can remove k-header class
  Removed from the spec as the class seems to be obsolete
• we should use k-tabstrip-item instead of k-item
  Both classes would be present for now as the styles in the themes are attached to k-item class and some in some suites only the k-item class is present, thus replacing it would impose a breaking change
• check if we can remove k-tab-on-top class as mentioned here -  Unify rendering for ColumnMenu
  Removed from the spec as the class seems to be obsolete

CheckBox

• should checked CheckBoxes have k-checked class
  both the class k-checked and the state :checked hold the styles. However, we should keep the class for consistency - we are adding state classes for buttons, inputs, etc- k-hover, k-focus, etc. So following the same logic, we should add k-check to the checked checkox as well .
• add a template with checked CheckBoxes

ImageEditor

• The form label "Lock aspect ratio:" should become a label of the checkbox, following the design guidelines.

DateTimePicker, others

• add missing k-time-accept, k-time-cancel to adaptive buttons
• check if we can replace k-calendar-container and k-list-container with k-datetime-container - ref