fpga-bootloading-changes-phase-2-PR-1

[coolbreeze413]

phase-2 changes for adding support for appfpga and m4app flashing/loading. Summary of changes:

• this takes the phase-1 changes as base, and adds further
• changed flash memory map a little bit
• added image_info in the image metadata segment
• added set_image_info() and get_image_info() to write/read the image_info metadata
• use --mode argument (always required) and set the image_info accordingly (read-modify-write metadata)

We should review the phase-1 PR and then decide on this one, hence draft PR.

Refer here for detailed description:

1. https://github.com/QuickLogic-Corp/qorc-sdk/blob/flashing-loading-changes-for-fpga/qf_apps/qf_bootloader/flashing-loading-changes.rst
2. https://github.com/QuickLogic-Corp/qorc-sdk/blob/flashing-loading-changes-for-fpga/qf_apps/qf_bootloader/flash_memory_map.rst

[coolbreeze413]

Added documentation for appfpga and mode arguments, added more detailed doc on the flash memory address-map currently used on QuickFeather (2MB Flash). Moved the documentation from the q-series readme into the main readme. Added documentation for bootloader upgrade from the qorc-sdk latest. [Older bootloader can still be used, but will only always load the m4app image, if flashed]