Allow to change icon for year select in calendar header

### Feature Description

Right now, icon for calendar year select is hardcoded in source code - https://github.com/angular/components/blob/fd47a0e60dd9ab50d9f923713ca60a7fd21ccc16/src/material/datepicker/calendar-header.html#L11

Please, add ability to override it (maybe via `icon registry`), because buttons below uses `matIcon`

### Use Case

_No response_

Start with src/material/datepicker/calendar-header.html at the linked year-select icon, then read the surrounding datepicker calendar-header entry point and the icon registry usage for matIcon buttons. Done means the year-select icon can be overridden without changing the source template directly, with the existing calendar header behavior preserved.

Written by the indexing model from the issue text.