Provide shell completions for subcommands: wrap, unwrap, report

- consider at least bash, fish and zsh
- As a nice touch, generate completion files automatically from the program itself.

Ideally a user wants to write something like `funkoverage completion zsh` and redirect the output to a folder mentioned in his `$fpath` . This feature can be used by the packager as well.

see https://github.com/junegunn/fzf?tab=readme-ov-file#setting-up-shell-integration

Start at the CLI entry point that handles the `wrap`, `unwrap`, and `report` subcommands, then trace how `funkoverage` parses commands. Define the completion behavior for bash, fish, and zsh, including `funkoverage completion zsh` output suitable for redirection. Done means each listed shell can complete the subcommands and the generated files work for users and packagers.

Written by the indexing model from the issue text.