[shell] Make ALT-C use the absolute path to the selected directory (#3688)

Rationale: this way the resulting cd command that ends up in the shell
history can be reused to get to the same location regardless of
the current working directory.

Co-authored-by: LangLangBart <92653266+LangLangBart@users.noreply.github.com>

shell/key-bindings.zsh

@@ -78,7 +78,7 @@ fzf-cd-widget() {
     return 0
   fi
   zle push-line # Clear buffer. Auto-restored on next prompt.
-  BUFFER="builtin cd -- ${(q)dir}"
+  BUFFER="builtin cd -- ${(q)dir:a}"
   zle accept-line
   local ret=$?
   unset dir # ensure this doesn't end up appearing in prompt expansion