chore: update emoji list to Unicode v15.1 and add emoji list generator script

[Snxwman]

I've written the script to generate the emoji list and have updated the list to have all the emojis in Unicode v15.1 (current version) with their proper names.

Due to some issues in Neovim (e.g. neovim/neovim#7151), emojis that are composed from multiple emojis or use modifiers do not render properly. Currently this breaks all skin tone emojis, almost all flags, most gender modified emojis, and a few random emojis. I have commented these lines out but left them in the file for visibility.

Also added a line to .gitignore so when the script is run, the downloaded emoji source doesn't get tracked by git.

[Snxwman]

I will add the shortcodes from iamcal/emoji-data to the list and generator script before you merge.