Update the Grid Editing and Date-Time editors topics with the new features related to the inputFormats

[ddaribo]

Update the Editing Templates section of the Grid editing topic with the newly added in v.18.2.x editorOptions feature for the built-in date-time editors in the IgxGrid - Changelog entry here.

Also update the Date-Time editor, Date Picker, Date-Rang Picker and Time Picker topics section about Display and input format with information about the new behavior, where the displayFormat will be used as input format in case inputFormat is not set and the former contains only numeric date-time parts.