moss::cli: Add dynamic shell completions

[otherJL0]

This PR uses the unstable dynamic completion feature of clap_complete to provide completion candidates at runtime for certain moss commands. This PR adds package names as completion candidates to the subcommands moss install and moss remove and introduces some simple benchmarks with criterion. I'll keep this as a draft for now until the rustqlite migration is complete.

[otherJL0]

@ermo I've been fiddling with this PR after migration to rustqlite and I think it's ready for review. This one is a little more involved and requires some changes to the moss stone.yaml file for the completions. I'll attach the commands below for each shell to use to export the runtime completions for local testing too. This is my first time working with criterion and the database code for moss so let me know if I'm committing any anti-patterns.

Right now the dynamic completion is enabled for moss install and moss remove only.

echo 'source <(COMPLETE=bash moss)' >> ~/.bashrc
echo 'source <(COMPLETE=zsh moss)'  >> ~/.zshrc 
echo 'COMPLETE=fish moss | source'  > ~/.config/fish/completions/moss.fish

[otherJL0]

Made some improvements to the completion output. When testing on my machine, I discovered that fish shell has implemented their own moss completion script with dynamic completion populated using native fish functions by filtering through moss list commands: https://github.com/fish-shell/fish-shell/blob/master/share/completions/moss.fish
If the clap dynamic completions are merged and exported, I think the clap completions will take precedence over the embedded fish moss completions but I just wanted to highlight this conflict because it made it a little difficult to test on fish shell on my local machine.

The fish completions provided both package name and package summary as part of their completions which inspired me to borrow their approach: