Replace clap with pico_args
This pull request replace the clap command line argument parser with pico_args.
This has the following benefits:
- Reduces binary size by 332 KiB (when compiled with
RUSTFLAGS='-C codegen-units=1 -C panic=abort -C link-args=-s' cargo build --release)
- Reduced time to compile by 3 seconds
The UI is mostly the same. The help information is more colorful now. Pico_args parses arguements linearly so error messages will display the first argument not found (whereas clap would tell you all of them).