rauc: add configuration for QEMU x86 and x86-64

The configuration files are very similar to what is available for
Raspberry Pi 4. In general all the files, except for COMPATIBLE
setting can become identical over time, as we move to GPT partition
identifiers to identify the slots.

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