Add command line help for cooker

cooker in Qt 6.8.0 binaries on Windows does not give any output whatsoever

C:\Qt\6.8.0\msvc2022_64\bin>cooker

C:\Qt\6.8.0\msvc2022_64\bin>cooker -h

C:\Qt\6.8.0\msvc2022_64\bin>cooker --help

C:\Qt\6.8.0\msvc2022_64\bin>cooker xya

Neither does the executable metadata give any description except 'Qt Cooker' :

It should arguably

• Print some info about what it is good for when launched without arguments
• Print extended help if launched with -h / --help arguments