This commit refactors the ulp component.
Files are now divided based on type of ulp, viz., fsm or risc-v.
Files common to both are maintained in the ulp_common folder.
This commit also adds menuconfig options for ULP within the ulp
component instead of presenting target specific configuations for ulp.
riscv32-esp-elf toolchain (used for ESP32-C3) can also be used for
ESP32-S2 RISC-V ULP coprocessor.
This removes the riscv-none-embed-gcc toolchain which was originally
used for the ULP, and updates the docs and CMake files to use
riscv32-esp-elf.
Some flags are cleaned up and workarounds removed from CMake toolchain
file.
