tests/arch/common: Add tests for the arch timing API

Simple tests to check the sanity of implementations. As with any tests
involving time, a constant "tolerance" of 10% is used in some of the
measurements.

Checks are basically answering the questions 1) "is time always
increasing?" and 2) "at a somewhat constant pace?". And some tests for
the time conversion, answering "is the elapsed time in nanoseconds
somewhat coherent?".

As timing and emulation are a somewhat dangerous combination,
`testcase.yaml` exclude CONFIG_QEMU_TARGET=y from tests.

Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>