feat: Add version response & cli command

[Septias]

closes #41
closes #50

This pr parses every message received for the /version command. Because the msg is loaded then anyway, this creates room for improvements because the msg will be loaded in the respective handlers again atm.

[link2xt]

A test would be nice to have, especially since it would have caught an env! crash without a review.

[Septias]

The cargo build script now creates the version file for the bot. This way it doesn't panic if it's not run with cargo and the tarball will have the version available as it is copied from the bot-data folder.

[link2xt]

Fine code-wise, I'm not approving yet because I want to test this first.

[link2xt]

I pushed a test and a fix commit to this branch

[link2xt]

@Septias I rebased the branch but now GH displays only the commiter (me) because you don't have your email confirmed with GH.

[link2xt]

Ok, there is a problem introduced in #29 (see comment #29 (comment)) still there. github-bot version fails because addr is not set, even though address and password is definitely not needed to just print the version.

And if you actually set these variables, output of version subcommand on stdout is:

Generated genisis group join QR-code at ./bot-data/genesis_invite_qr.png
Generated 1:1 invite QR-code at ./bot-data/1o1_invite_qr.png
393e3e4

EDIT: fixed this too

[Septias]

@Septias I rebased the branch but now GH displays only the commiter (me) because you don't have your email confirmed with GH.

Can we squash merge and just manually add me?

[Septias]

Looks good to me, you can merge if you want.