Add InPlaceFunction to mediautils

This utility class is an almost drop-in replacement for std::function
which never allocates, and always stores the functional object in an
in-line buffer of parametrizable size.

Test: atest inplace_function_tests
Bug: 238654698
Change-Id: I48a7c16fad7673ccf03f8ae83036f2c96d76e994
3 files changed