Shell integration: Dont modify ~/.zshrc

Instead use the ZDOTDIR env var to load the shell integration code

shell-integration/zsh/.zshenv

@@ -0,0 +1,9 @@
+if [[ -o interactive && -v ZDOTDIR && -r "$ZDOTDIR/kitty.zsh" ]]; then source "$ZDOTDIR/kitty.zsh"; fi
+if [[ -v KITTY_ORIG_ZDOTDIR ]]; then
+    export ZDOTDIR="$KITTY_ORIG_ZDOTDIR"
+    unset KITTY_ORIG_ZDOTDIR
+else
+    unset ZDOTDIR
+fi
+if [[ -v KITTY_ZSH_BASE && -r "$KITTY_ZSH_BASE/.zshenv" ]]; then source "$KITTY_ZSH_BASE/.zshenv"; fi
+unset KITTY_ZSH_BASE