feat(preview-tui): handle quoting in start_preview more robustly

[musjj]

This PR makes the script more resistant to naughty filenames.
The script now depends on bash for the following features:

• Arrays
  Correctly creating and passing argument lists is now simple
• Parameter transformation
  ${parameter@Q} makes it easy to correctly quote a string so that it can be safely re-evaluated by the interpreter later.

On iTerm, the shell command used to render the preview is now passed to osascript via a named pipe: $FIFO_OSASCRIPT.
By not embedding the shell command directly, we now no longer need to worry about osascript's quoting rules. It's not perfect, because $SHELL and $TMPDIR might contain naughty characters, but it's quite unlikely to happen.

Fix #1614

[luukvbaal]

Thanks! I had a similar commit laying around but there were problems and hadn't gotten around to fixing them yet.

I can check windows terminal tomorrow and iterm through a VM but other testers are welcome.

[N-R-K]

Looks OK to me (lightly tested). A couple comments:

• The $FIFO_OSASCRIPT thing is new. I can guess what it's doing and why but the commit body should explain it too.
• Additionally the PR description should be included in the commit body. It's much more convenient to have the rationale behind a change documented in the commit message so that it can be viewed directly in git instead of hunting down PR/issues in some web ui.

[luukvbaal]

I pushed a commit that is noticeably faster when toggling preview-tui (comparable to pre env refactor). I confirmed that it works with xterm, tmux, kitty and wezterm as previewer.

I have yet to test iTerm and Windows Terminal.

[luukvbaal]

iTerm does work, but not with the bash version that comes by default on (my VM's) MacOS. It does not support the @Q expansion.
I was able to make it work by reverting back to escaping ourselves, perhaps we want to do that to avoid bash version requirements?

[jarun]

We can document if it's straightforward to upgrade the bash.

[musjj]

Nice, that's probably faster than a manual loop. It works pretty well for me.

[luukvbaal]

I must say I am not a big fan of writing the osascript command to a file. We already had a working solution by properly escaping that can now be replaced by two simple bash parameter expansions. The latest commit does that, what do you guys think?
Besides, it is not really a FIFO, just a file and another (unnecessary IMO) one that we must clean up after ourselves at that.

It works on iTerm (with the shipped bash version) and Windows Terminal. Although I made some minor changes after testing on windows so I will test once more tomorrow.

EDIT: All working well in my testing.

[jarun]

Thank you!