feat(mat-calendar): Allow to hide header

### Feature Description

The mat-calender component shpuld have a hide header option or should allow null for headerComponent to allow removing the header.

### Use Case

Display component only for a certain month. Navigation through months is done outside the calendar component.

Start by locating the Angular Material mat-calendar implementation and the headerComponent API. Review how the calendar header is selected and check existing calendar tests before deciding how a hidden or null header should be represented. Done means the header can be omitted while the calendar still displays the requested month, with tests covering the new option.

Written by the indexing model from the issue text.