Harden apt-mark defined type

Harden apt-mark defined type

Prior to this commit the title parameter of this defined
type was not properly validated. This means that it could have been
possible to use a resource title outside of the normal bounds of
a package name.

Additionally the `onlyif` and `command` parameter values were
interpolated strings meaning that it may have been possible to
execute unsafe code on the remote system.

This commit fixes the above issues by adding a regex to check that the
resource title is a valid apt package name and also breaks out the
`onlyif` and `command` parameter values in to arrays of args ensuring
that the commands executed in a safe manor on the remote system.

The exception in this commit is the `unless_cmd`. This has not been
broken out in to an array of args due to the requirement of the command.
This is a reasonable trade of however due to the fact that action is
created from known enum values and title would be pre-validated.
This is also explained in mark.pp:20.