fix(completions/zsh.rs): Maybe fix completions with mixed positionals and subcommands

Optional positionals mixed with subcommands will still break this, since
I can't see how to tell which element of $line is the command than.
Mixing optional positionals with subcommands is a bit weird and awkward
though...

src/completions/zsh.rs

@@ -230,15 +230,18 @@ fn get_subcommands_of(p: &Parser) -> String {
     format!(
         "case $state in
     ({name})
-        curcontext=\"${{curcontext%:*:*}}:{name_hyphen}-command-$words[1]:\"
-        case $line[1] in
+        words=($line[{pos}] \"${{words[@]}}\")
+        (( CURRENT += 1 ))
+        curcontext=\"${{curcontext%:*:*}}:{name_hyphen}-command-$line[{pos}]:\"
+        case $line[{pos}] in
             {subcommands}
         esac
     ;;
 esac",
         name = p.meta.name,
         name_hyphen = p.meta.bin_name.as_ref().unwrap().replace(" ", "-"),
-        subcommands = subcmds.join("\n")
+        subcommands = subcmds.join("\n"),
+        pos = p.positionals().len() + 1
     )
 }
 
@@ -285,7 +288,7 @@ fn get_args_of(p: &Parser) -> String {
         String::new()
     };
     let sc = if p.has_subcommands() {
-        format!("\"*:: :->{name}\" \\", name = p.meta.name)
+        format!("\"*::: :->{name}\" \\", name = p.meta.name)
     } else {
         String::new()
     };

tests/completions.rs

@@ -101,12 +101,14 @@ _myapp() {
 '--version[Prints version information]' \
 "::file -- some input file:_files" \
 ":: :_myapp_commands" \
-"*:: :->myapp" \
+"*::: :->myapp" \
 && ret=0
     case $state in
     (myapp)
-        curcontext="${curcontext%:*:*}:myapp-command-$words[1]:"
-        case $line[1] in
+        words=($line[2] "${words[@]}")
+        (( CURRENT += 1 ))
+        curcontext="${curcontext%:*:*}:myapp-command-$line[2]:"
+        case $line[2] in
             (test)
 _arguments -s -S -C \
 '--case=[the case to test]' \
@@ -390,12 +392,14 @@ _my_app() {
 '--version[Prints version information]' \
 "::file -- some input file:_files" \
 ":: :_my_app_commands" \
-"*:: :->my_app" \
+"*::: :->my_app" \
 && ret=0
     case $state in
     (my_app)
-        curcontext="${curcontext%:*:*}:my_app-command-$words[1]:"
-        case $line[1] in
+        words=($line[2] "${words[@]}")
+        (( CURRENT += 1 ))
+        curcontext="${curcontext%:*:*}:my_app-command-$line[2]:"
+        case $line[2] in
             (test)
 _arguments -s -S -C \
 '--case=[the case to test]' \