SHA acceleration integrated to mbedTLS incl. TLS sessions
Uses hardware SHA acceleration where available, fails over to software where not available.
Ref TW7112
See merge request !232
SHA hardware allows each of SHA1, SHA256, SHA384&SHA512 to calculate digests
concurrently.
Currently incompatible with AES acceleration due to a hardware reset problem.
Ref TW7111.
Required at project level because some components use header files in
other components' submodules, and one component with a
submodule (esptool.py) doesn't have or need a component.mk.
Simplifies examples of embedding a certificate file or a root cert.
This is a much cruder mechanism than the full flash filesystem we want
eventually, but still sometimes useful.
Used by mbedTLS to set MBEDTLS_CONFIG_FILE in all components.
This change sets CFLAGS/etc at the project level and then exports those
variables for components, rather than setting them independently each time
a component Makefile is invoked.
