refactor: handle $0 according to the Zsh plugin standard (#10518)

For details and rationale, see:
https://zdharma-continuum.github.io/Zsh-100-Commits-Club/Zsh-Plugin-Standard.html

Closes #10518

plugins/zsh-navigation-tools/zsh-navigation-tools.plugin.zsh

@@ -11,6 +11,7 @@
 # https://zdharma-continuum.github.io/Zsh-100-Commits-Club/Zsh-Plugin-Standard.html
 0="${${ZERO:-${0:#$ZSH_ARGZERO}}:-${(%):-%N}}"
 0="${${(M)0:#/*}:-$PWD/$0}"
+
 export ZNT_REPO_DIR="${0:h}"
 export ZNT_CONFIG_DIR="$HOME/.config/znt"