sysota: generate RAUC configuration file from template

As we add support for additional boards, doing it by copying and modifying a file with relatively few parts changing got tedious.

The change adds half a dozen new variables for selecting the boot loader type, various strings and directories. The defaults are safe, even if unused, for all kinds of boards. The machine-specific overrides tune the bootloader used by each board and provide proper identification strings.

Signed-off-by: Zygmunt Krynicki zygmunt.krynicki@huawei.com