Improve action new-tab

[abatkin]

Improvements to zellij action new-tab:

• setting --cwd <dir> no longer requires specifying a layout
• add --run <command> (and --args <arg>) to run a command
• add --edit <filename> to launch editor of the specified file

A few other cleanups along the way:

• Update .gitignore to add .idea project files (JetBrains tools like CLion/RustRover)
• Update .gitignore to add docker-compose.override.yml (for example to set additional SELinux settings when running tests)
• Quote "true" in docker-compose.yml since otherwise it could be treated as a boolean and rejected

Fixes #2981

[abatkin]

A few questions:

1. Should an entry be added to CHANGELOG.md?
2. Should the .wasm files be checked in? I'm guessing no, so I can pull those back out (otherwise there will be conflicts everywhere, right?)
3. A few .snap files had to be updated, since it was necessary to change the NewTab interface, is that okay? I don't see another way around changing that, but I hope that doesn't break anything else that I haven't thought about
4. TerminalAction gets directly serialized now, and I'm not sure if that's appropriate, or if there should be an intermediate representation (that will be otherwise identical, at least for now) for the client-server datamodel

[devyntk]

Bumping this issue - currently this is blocking me from implementing some extremely useful scripting that I use all the time in tmux. The ability to create a new tab with a specified command in it seems like an extremely basic and necessary feature for any amount of scripting in Zellij, and is a major detriment to adoption of Zellij in my team.

[abatkin]

A few updates:

• rebased from main, fixed conflicts
• removed .wasm files from PR since they will always conflict, presumably whoever handles releases will update those

Tests pass, and I've been playing around and it seems to work properly.