feat: Option to put tuntox password in copied URL

Thanks for this great package!

These changes allow faster sharing & connecting with tuntox links made using crdt-copy-url. This changed behavior is toggleable using crdt-tuntox-password-in-url, which defaults to nil to preserve existing behavior and to remind users that they should be sure they can trust their sharing channel before turning this on.

If you set crdt-tuntox-password-in-url to t, then the URL made by crdt-copy-url will put the password in plaintext into the query string of the URL. When calling crdt-connect, pasting in the URL with the query string password will automatically get and use the password without requiring a separate prompt. This lets users (like my friend and I) who already have a secure/encrypted text channel send each other the full link with password in a single copy-paste, instead of having to copy-paste the URL followed by typing out the password again in two separate steps.

I saw there's also a development branch, but I wasn't sure what state that branch was in or when that might make it to the ELPA version, so that's why this merge request targets master -- it should apply pretty cleanly onto development as well though so let me know if I should rebase.