Brings SMF framework closer into alignment with accepted Hierarchical State
Machine operation by:
1. Allowing 'programming by difference' by having some child states handle
events and prevent propagation up to the parent run actions while others
propagate events up to a common handler in a parent state.
2. Optionally allow initial transitions within a parent state to determine
the most nested child state to transition to.
3. Adding a test case for `CONFIG_SMF_INITIAL_TRANSITION` and
`smf_set_handled()`
4. Updating documentation for the new API (and fixing some references)
There was discussion in https://github.com/zephyrproject-rtos/zephyr/issues/55344
about not making the initial transition a Kconfig option, but I'm not sure
of any way else of doing it without permanently adding a pointer to each
`smf_state` entry, which is a problem for resource-constrained devices.
This does not fix https://github.com/zephyrproject-rtos/zephyr/issues/66341
but documentation has been updated to warn users of the issue.
Signed-off-by: Glenn Andrews <glenn.andrews.42@gmail.com>
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