Not all devices have enough heap to fit a simulated heap block device,
however using a simulated heap block device is preferred if available
(reduced flash wear, faster testing).
Added MBED_TEST_SIM_BLOCKDEVICE for tests that only need a simulated
block device (wear_leveling + resilience), and added support for targets
that are known to have enough heap.
Tools will figure out if user passed in a custom path (to indicate configration file for module) or whether they used a keyword (to indicate they'd like to use an mbed OS configuration)
jeromecoutant
Juha Ylinen
Senthil Ramakrishnan
Christopher Haster
Sarah Marsh