feat: add option to use tmux display-popup (#3058)

This is a "continuation" of #1177 - which was a draft that used FIFOs
(named pipes) to get output from the popup, however this causes popup
not being closed properly, so in this PR I use tmpfile to store the
result and read after popup closes. @ellie could you review this PR
please?

P.S. Thank you @immae for sharing your idea!

## Feature
+ Option to use tmux popup window in `config.toml`
+ Customize window width/height in `config.toml`
+ Tmux display-popup for `zsh, bash, fish`

## Checks
- [x] I am happy for maintainers to push small adjustments to this PR,
to speed up the review cycle
- [x] I have checked that there are no existing pull requests for the
same thing

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Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

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