support multi rtos in qemu platform(rtos & arm)

version 1.0.0:
    support ezos rt-thread freertos threadx run on riscv-virt
to do:
    - add port doc
    - add arm platform
    - fullfill ezos

environment:
    1. qemu
    2. riscv toolchain, you can use https://download.nucleisys.com/upload/files/toolchain/gcc/nuclei_riscv_newlibc_prebuilt_linux64_2024.06.tar.bz2
    3. cmake & make

usage:
    1. type  ./build.sh, choose which cmd, which rtos, which target
    2. use run, for example: build with ./build.sh build riscv freertos, run with ./build.sh run riscv freertos
    3. use gdb, for example: build with ./build.sh build riscv freertos, run with ./build.sh gdb riscv freertos, open another terminal, then type riscv64-unknown-elf-gdb out/multi_rtos.out.
       In gdb command, type tar rem:1234, then type load & c to run