Compatibility: delay() should call yield()

In official AVR Arduino core, delay() is based on yield(), which is turn has weak binding and is overridable.
I am asking that delay() on any Arduino platform must call yield() at least once, preferably at the end of delay(), for compatibility with libraries like Scheduler and similar implementations.

Start by locating the Arduino core entry points for delay() and yield(), then inspect how delay() currently behaves on this ATMEGA4809 core. Done means delay() invokes yield() at least once, preferably at the end, while preserving compatibility with Scheduler and similar libraries.

Written by the indexing model from the issue text.