QoL fixes

[IPMegladon]

• Fix few remaining job handler instances not returning implementation.
• Add error messages such that incorrect job implementations do not fail silently.
• Change some common Exception errors to normal prints + sys.exit.
• Add code similar to frida-tools to support also attaching by application identifier instead of name. I.e. objection -n "RootBeer Sample" start and objection -n "com.scottyab.rootbeer.sample" start now works.