Rationalise compiler flags and esp32 improvements

[mikee47]

Fix build inconsistencies and move common settings from arch. into main Sming to reduce code duplication.

• Rationalise compiler flags, add COMPONENT_CPPFLAGS
• Add SMING_C_STD to debug vars
• Get rid of obsolete Esp32 build settings (these related to pre-CMake builds)
• Add Undef, UndefWrap, Wrap, DefSym linker function
• Split Esp32 linker settings out. Use one file per esp32 component to simplify tracking settings and changes with IDF.
• Simplify meminfo, rename as fwMeminfo.txt and remove old/saved
• Wrap esp32 printf functions so they don't get pulled in from C library. Saves about 60K flash (and a little RAM).

[mikee47]

The codacy warning is about strlen - there are other instances of this in the framework. We could rewrite using strnlen instead but that increases code complexity and not sure it's warranted...