Remove clap as a dependency

[marlonbaeten]

Although clap is an excellent crate, it is not intended for use with a setuid program. The size of clap adds an unreasonable burden of reviewing it and its dependencies from the security perspective of a setuid program. Also, to be compliant of how sudo processes arguments, we need some custom parsing logic. Therefore, the advantages of using clap do not outweigh the disadvantages in our case.