[Virtio-fs] [virtiofsd] MR opened: Add capability to create security context (SELinux) during file creation

[virtiofs-bot at sinrega.org]

Fuse has capability to send security context of file (SELinux), during file creation if server opted for it (FUSE_SECURITY_CTX). Enable this feature and opt for SECURITY_CTX if user passed option "-o security_label". This should help with support SELinux on top of virtiofs.

As of now file creation and security context setting operation are non-atomic. In some cases these can be made atomic. These additional changes I will follow in separate MR once these changes are merged. Otherwise it becomes too much of code.

Please review.

Vivek
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https://gitlab.com/virtio-fs/virtiofsd/-/merge_requests/102