Update "make translations" to reduce build requirements

Previously, preparing translations required rebar3 and:
  ./configure --enable-tools
  make
  make translations

With this change it works with rebar3 and mix, just running:
  ./configure
  make translations

Makefile.in

@@ -141,6 +141,8 @@ ifeq "$(REBAR_VER)" "6"
   RELIVECMD=$(ESCRIPT) rel/relive.escript && MIX_ENV=dev RELIVE=true $(IEX) --name ejabberd@localhost -S mix run
   REL_LIB_DIR = _build/dev/rel/ejabberd/lib
   COPY_REL_TARGET = dev
+  GET_DEPS_TRANSLATIONS=MIX_ENV=translations $(REBAR) $(GET_DEPS)
+  DEPSDIR_TRANSLATIONS=deps
 else
 ifeq ($(REBAR_ENABLE_ELIXIR),true)
   ELIXIR_LIBDIR_RAW=$(shell elixir -e "IO.puts(:filename.dirname(:code.lib_dir(:elixir)))" -e ":erlang.halt")
@@ -169,6 +171,8 @@ endif
   RELIVECMD=$(REBAR) relive
   REL_LIB_DIR = _build/dev/rel/ejabberd/lib
   COPY_REL_TARGET = dev
+  GET_DEPS_TRANSLATIONS=$(REBAR) as translations $(GET_DEPS)
+  DEPSDIR_TRANSLATIONS=_build/translations/lib
 else
   SKIPDEPS=skip_deps=true
   LISTDEPS=-q list-deps
@@ -228,7 +232,8 @@ options: all
 	tools/opt_types.sh ejabberd_option $(EBINDIR)
 
 translations:
-	tools/prepare-tr.sh $(DEPSDIR)
+	$(GET_DEPS_TRANSLATIONS)
+	tools/prepare-tr.sh $(DEPSDIR_TRANSLATIONS)
 
 doap:
 	tools/generate-doap.sh
@@ -647,7 +652,7 @@ help:
 	@echo "  doap           Generate DOAP file"
 	@echo "  edoc           Generate edoc documentation (unused)"
 	@echo "  options        Generate ejabberd_option.erl"
-	@echo "  translations   Extract translation files (requires --enable-tools)"
+	@echo "  translations   Extract translation files"
 	@echo "  TAGS           Generate tags file for text editors"
 	@echo ""
 	@echo "  dialyzer       Run Dialyzer static analyzer"

configure.ac

@@ -256,7 +256,7 @@ AC_ARG_ENABLE(system_deps,
 esac],[if test "x$system_deps" = "x"; then system_deps=false; fi])
 
 AC_ARG_ENABLE(tools,
-[AS_HELP_STRING([--enable-tools],[build development tools: ejabberd-po, etop (default: no)])],
+[AS_HELP_STRING([--enable-tools],[build development tools: etop (default: no)])],
 [case "${enableval}" in
   yes) tools=true ;;
   no)  tools=false ;;

mix.exs

@@ -132,6 +132,8 @@ defmodule Ejabberd.MixProject do
 
   defp cond_deps do
     for {:true, dep} <- [{config(:pam), {:epam, "~> 1.0"}},
+                         {Mix.env() == :translations,
+                          {:ejabberd_po, git: "https://github.com/processone/ejabberd-po.git"}},
                          {config(:redis), {:eredis, "~> 1.2.0"}},
                          {config(:sip), {:esip, "~> 1.0"}},
                          {config(:zlib), {:ezlib, "~> 1.0"}},

rebar.config

@@ -25,8 +25,6 @@
 {deps, [{base64url, ".*", {git, "https://github.com/dvv/base64url", {tag, "1.0.1"}}},
         {cache_tab, ".*", {git, "https://github.com/processone/cache_tab", {tag, "1.0.30"}}},
         {eimp, ".*", {git, "https://github.com/processone/eimp", {tag, "1.0.22"}}},
-        {if_var_true, tools,
-         {ejabberd_po, ".*", {git, "https://github.com/processone/ejabberd-po", {branch, "main"}}}},
         {if_var_true, pam,
          {epam, ".*", {git, "https://github.com/processone/epam", {tag, "1.0.14"}}}},
         {if_var_true, redis,
@@ -283,6 +281,7 @@
                                       {copy, "ejabberd.yml.example", "conf/ejabberd.yml.example"},
                                       {copy, "test/ejabberd_SUITE_data/ca.pem", "conf/"},
                                       {copy, "test/ejabberd_SUITE_data/cert.pem", "conf/"}]}]}]},
+            {translations, [{deps, [{ejabberd_po, ".*", {git, "https://github.com/processone/ejabberd-po", {branch, "main"}}}]}]},
             {test, [{erl_opts, [nowarn_export_all]}]}]}.
 
 {alias, [{relive, [{shell, "--apps ejabberd \