Add drpai installation to mistysom-image + some docker permission fixes

[matinlotfali]

Because this installation is only for RZ/V2L, I am not adding the package to the meta-mistysom repo.

• Instead, I modify the mistysom-image.bbappend file inside the start.sh.

To do so, I noticed there are permission issues that were causing errors. The meta-mistysom directory was owned by the root user instead of yocto.

• So I fixed the permissions as well.