ksud: refine su and make it compitable with MagiskSU

Supported features:

1.  --mount-master, -M, -mm which would make the command run in global mount namespace.
2. - user to switch a specific user's shell.
3. -v, -V to print version code and name.

fix #330 #306 #305 #32

userspace/ksud/Cargo.toml

@@ -32,6 +32,7 @@ rust-embed = { version = "6.4.2", features = [
     "compression", # must clean build after updating binaries
 ] }
 which = "4.2.2"
+getopts = "0.2.21"
 
 [target.'cfg(any(target_os = "android", target_os = "linux"))'.dependencies]
 sys-mount = { git = "https://github.com/tiann/sys-mount" }