There is no ccomp timer on C3, which means our performance tests will start
failing again due to variance caused by cache misses.
This MR adds TEST_PERFORMANCE_CCOMP_ macro that will only fail
performance test if CCOMP timer is supported on the target
New unity component can be used for testing other applications.
Upstream version of Unity is included as a submodule.
Utilities specific to ESP-IDF unit tests (partitions, leak checking
setup/teardown functions, etc) are kept only in unit-test-app.
Kconfig options are added to allow disabling certain Unity features.
spi test: Prime the flash cache before each test to minimise flash cache misses.
VFS performance test: Increase the number of runs to minimise influence of an isolated bad run.
