dns_inwx: fix IDN zone detection without python dependency (#7056)

* dns_inwx: fix IDN zone detection without python dependency

INWX returns zone names in Unicode form (e.g. lünenschloß.de) even when
the domain was registered as an IDN. When acme.sh passes the SAN in
punycode (xn--lnenschlo-o1a42a.de), _contains never matches and
_get_root falls through to the TLD, placing the TXT record in the wrong
zone.

Previous fix used python3 which is not available in all environments
(BusyBox, BSD, minimal containers). Replace with _idn()-based approach:
extract <string> values from the nameserver.list XML response, encode
each via _idn(), and compare to $h. When a match is found, use the
original Unicode zone name for createRecord.

Fixes #7038

* dns_inwx: fix shebang, use _egrep_o, shfmt cleanup

- Revert shebang to #!/usr/bin/env sh (POSIX sh, fixes ShellCheck)
- Replace grep -o with _egrep_o for portability
- shfmt -i 2: drop backslash continuation after pipe, fix indentation

Requested by @neilpang

* fix: drop closing </string> from _egrep_o pattern to avoid sed delimiter collision

---------

Co-authored-by: bluenenschloss <bernd.luenenschloss@7p-group.com>

dnsapi/dns_inwx.sh

@@ -312,6 +312,22 @@ _get_root() {
       _domain="$h"
       return 0
     fi
+    # IDN fallback: INWX returns Unicode zone names; when $h is ACE/punycode,
+    # encode each zone name via _idn() and compare — no python dependency.
+    if _contains "$h" "xn--"; then
+      _zone_unicode=$(printf "%s" "$response" | _egrep_o '<string>[^<]*' |
+        sed 's/<[^>]*>//g' | while IFS= read -r _z; do
+        if [ "$(_idn "$_z")" = "$h" ]; then
+          printf "%s" "$_z"
+          break
+        fi
+      done)
+      if [ -n "$_zone_unicode" ]; then
+        _sub_domain=$(printf "%s" "$domain" | cut -d . -f 1-"$p")
+        _domain="$_zone_unicode"
+        return 0
+      fi
+    fi
     p=$i
     i=$(_math "$i" + 1)
   done