shell-scripts: Use [[ instead of [ where possible

Replace all occurrences of [ with [[ in bash and zsh scripts and
configs.
Performance wise it makes sense to use the builtin instead of calling an
external command also when from a functionality stand point `test` would
suffice.

.config/zsh/autoload/git-submodule-rm

@@ -7,7 +7,7 @@
 local toplevel="$(git rev-parse --show-toplevel)" || return
 
 # Exit if no arguements were given
-[ $# -gt 0 ] || return
+[[ $# -gt 0 ]] || return
 
 local separator=""
 for arg in "$@"; do
@@ -16,11 +16,11 @@ for arg in "$@"; do
 	# argument relative from git toplevel
 	local arg_from_git="${${arg:A}##$toplevel/}"
 	# argument has to exist
-	[ -e "$arg" ] || continue
+	[[ -e "$arg" ]] || continue
 	# argument has to exist in repo
-	[ -e "$toplevel/$arg_from_git" ] || continue
+	[[ -e "$toplevel/$arg_from_git" ]] || continue
 	# has to be a submodule
-	[ -e "$toplevel/.git/modules/$arg_from_git" ] || continue
+	[[ -e "$toplevel/.git/modules/$arg_from_git" ]] || continue
 
 	git submodule deinit -f  "$arg"
 	echo "command rm -rf \"$toplevel/.git/modules/$arg_from_git\""