Implement `--help` for decoder app CLI and additional CLI arg validation

[theHamsta]

This performs three changes to the decoder app CLI parsing

• put the arguments in a data structure to make them available for a --help command
• add some additional validation for CLI parameters (missing values, values that start with - since likely a mistake). Please let me know if the check for arguments not starting with - https://github.com/nvpro-samples/vk_video_samples/pull/62/commits/57e7addf8764ff917bb036288f7787118a89a317 adds too much code and should be omitted. Without it the actual parsing code is quite short https://github.com/nvpro-samples/vk_video_samples/pull/62/commits/be1317ca494d41ea3a8fa0061d2a7844aa406498. https://docs.rs/clap/latest/clap/ performs such a check which had prevented me often to run a program with unintended CLI flags
• Remove flags noTick as it seems to be unused. Let me know if they are indented to be used in future.

With this refactor a bug is fixed that prevented users to select -vv as strstr would also match the -v option.

PS: with the recent changes to master I'm now also seeing problems with the decoder with Turing.

[zlatinski]

Thank you, Stephan! The changes look good, but the change needs a rebase. Can you please do that? Also, we need to make sure this works on Windows.