Add Edky to Tools

[artob]

Edky converts Ed25519 public keys between various encoding formats, including IPFS's (aka libp2p, Multibase).

$ cargo binstall -y edky

$ edky convert -f ipfs -t hex z6MktwupdmLXVVqTzCw4i46r4uGyosGXRnR3XjN4Zq7oMMsw
d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a

$ edky convert -f ipfs -t base64url z6MktwupdmLXVVqTzCw4i46r4uGyosGXRnR3XjN4Zq7oMMsw
11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo

Pre-submit checklist

• This PR includes only one addition, removal, or edit.
• I have followed the Contribution Guidelines.
• I reviewed the IPFS Community Code of Conduct to ensure my submission meets the requirements.

[artob]

Oh hey, @bmann! Long time no talk!