Add --count to repeat the greeting

Implements: https://todo.hut.md/~reviewer/hello-hut/2

Read defaults from ~/.config/hello-hut/config.toml

Uses tomllib where available; on Python < 3.11 the file is ignored.

Add --time-of-day greetings

Add --shout to print the greeting in capitals

Use str.upper() so that accented names keep their accents.

cli: accept the name as a positional argument

`hello-hut Ada` reads better than `hello-hut --name Ada`.

Add greeting module and command-line entry point

hello-hut greets whoever is passed with --name, or "friend" by
default.