Command line parser improvements

• Related issues: #1224
• Requested reviewers: @malenovskyvl

Reason why this change is needed

• Some features are missing in the command line parser

Description of the change

• Added support for mandatory parameters
• Added placeholders for option values in the usage printout (e.g. -i <file>)
• Aligned usage printout more closely with style of IVAS_cod and IVAS_dec
• Improved error handling in command line parser internals
• Removed the requirement that all options must also have a short version (e.g. -i for --input)
• Completed old TODOs

Affected operating points

N/A