Minor XDGB edge cases

[mkysel]

This fixes 3 minor issues:

1. when the user does not specify a subcommand XDBG exits with code 0. This can be a bit confusing. Print help instead and exit with an error.

• I am open to other options. Printing to stderr and std::process:exit(1) are also pretty good choices.

2. Generate could not print help

$ cargo run --package xdbg -- generate -h
    Finished `dev` profile [unoptimized] target(s) in 0.19s
     Running `target/debug/xdbg generate -h`
The application panicked (crashed).
Message:  Command generate: Short option names must be unique for each argument, but '-i' is in use by both 'invite' and 'interval'
Location: /Users/martinkysel/.cargo/registry/src/index.crates.io-6f17d22bba15001f/clap_builder-4.5.23/src/builder/debug_asserts.rs:112

Now it can

3. Typo in loclalhosltls