Add Support for Vifm in Shell Prompt Segment

[Faddeev-Popov]

Description

This pull request adds support for the Vifm console file manager in the shell prompt segment of Powerlevel10k. It mirrors the integration approach used in PR #2572 for the Yazi file manager, providing a similar functionality for Vifm.

Background

Vifm currently does not have a built-in shell session level indicator. However, it can be implemented externally in various ways. The following implementation, adapted from Vifm Wiki - Shell Session Indication, works well with the commits included in this PR:

# ~/.zshrc

# Additional zshrc configuration ...

ZSH_PARENT="$(</proc/$PPID/comm)"

update_vifm_level() {
    if [[ $ZSH_PARENT == "vifm" ]]; then
        if [[ $1 == "enter" ]]; then
            VIFM_LEVEL=$((VIFM_LEVEL + 1))
        elif [[ $1 == "exit" ]]; then
            VIFM_LEVEL=$((VIFM_LEVEL > 0 ? VIFM_LEVEL - 1 : 0))
        fi
        export VIFM_LEVEL
    fi
}

# Increment `VIFM_LEVEL` if `ZSH_PARENT` is `vifm`
update_vifm_level "enter"

zshexit() {
    # Additional `zshexit` commands ...

    # Decrement `VIFM_LEVEL` if `ZSH_PARENT` was `vifm`
    update_vifm_level "exit"
}

References

• vifm
• Vifm Wiki