Add the possibility to have user bootloader components. This is performed
from an application/project, by creating bootloader components. To do so,
it is required to create a `bootloader_component` directory containing
the custom modules to be compiled with the bootloader.
Thanks to this, two solutions are available to override the bootloader now:
- Using hooks within a user bootloader component
- Using a user defined `main` bootloader component to totally override the
old implementation
Please check the two new examples in `examples/custom_bootloader`
* Closes https://github.com/espressif/esp-idf/issues/7043
The CPU might prefetch instructions, which means it in some cases
will try to fetch instruction located after the last instruction in
flash.text.
Add dummy bytes to ensure fetching these wont result in an error,
e.g. MMU exceptions
