simargs should print help on error

[LDprg]

Describe this problem

There should be an option to print the help on missing options.
This is currently as far as I understand not possible since the help can only printed after the data has been parsed (which fails if command is missing).

Version

v0.3.0

[jiacai2050]

If you miss an required option, simargs will log the option

zigcli/src/mod/simargs.zig

Line 720 in 82fae37

inline for (parser.opt_fields) |opt| {