Add missing template parameters to register_map and register_vector (#23625)

Add missing template args to register_map and register_vector to allow
this kind of bindings:

```
#include <emscripten.h>
#include <emscripten/bind.h>

std::map<std::string, std::string, std::greater<std::string>> get_map() {
  std::map<std::string, std::string, std::greater<std::string>> m;
  m["a"] = "b";
  m["c"] = "d";
  return m;
}

EMSCRIPTEN_BINDINGS(test_map) {
  emscripten::register_map<std::string, std::string, std::greater<std::string>>("StringMap");
  emscripten::function("get_map", &get_map);
}
```

Author: tikoyes94

site/source/docs/porting/connecting_cpp_and_javascript/embind.rst

@@ -1071,7 +1071,7 @@ Out of the box, *embind* provides converters for many standard C++ types:
 \*\*Requires BigInt support to be enabled with the `-sWASM_BIGINT` flag.
 
 For convenience, *embind* provides factory functions to register
-``std::vector<T>`` (:cpp:func:`register_vector`), ``std::map<K, V>``
+``std::vector<T, class Allocator=std::allocator<T>>`` (:cpp:func:`register_vector`), ``std::map<K, V, class Compare=std::less<K>, class Allocator=std::allocator<std::pair<const K, V>>>``
 (:cpp:func:`register_map`), and ``std::optional<T>`` (:cpp:func:`register_optional`) types:
 
 .. code:: cpp

system/include/emscripten/bind.h

@@ -2073,9 +2073,9 @@ struct VectorAccess {
 
 } // end namespace internal
 
-template<typename T>
-class_<std::vector<T>> register_vector(const char* name) {
-    typedef std::vector<T> VecType;
+template<typename T, class Allocator=std::allocator<T>>
+class_<std::vector<T, Allocator>> register_vector(const char* name) {
+    typedef std::vector<T, Allocator> VecType;
 #if __cplusplus >= 201703L
     register_optional<T>();
 #endif
@@ -2151,9 +2151,10 @@ struct MapAccess {
 
 } // end namespace internal
 
-template<typename K, typename V>
-class_<std::map<K, V>> register_map(const char* name) {
-    typedef std::map<K,V> MapType;
+template<typename K, typename V, class Compare = std::less<K>, 
+    class Allocator = std::allocator<std::pair<const K, V>>>
+class_<std::map<K, V, Compare, Allocator>> register_map(const char* name) {
+    typedef std::map<K,V, Compare, Allocator> MapType;
 #if __cplusplus >= 201703L
     register_optional<V>();
 #endif

test/embind/embind.test.js

@@ -1185,6 +1185,26 @@ module({
        });
     });
 
+    BaseFixture.extend("map_with_greater_comparator", function() {
+        test("std::map with std::greater comparator", function() {
+            var map = cm.embind_test_get_int_string_greater_map();
+            assert.equal(2, map.size());
+            assert.equal("one", map.get(1));
+            assert.equal("two", map.get(2));
+            map.delete();
+        });
+
+        test("std::map with std::greater comparator keys are sorted in reverse", function() {
+            var map = cm.embind_test_get_int_string_greater_map();
+            var keys = map.keys();
+            assert.equal(2, keys.size());
+            assert.equal(2, keys.get(0));
+            assert.equal(1, keys.get(1));
+            keys.delete();
+            map.delete();
+        });
+    });
+
     BaseFixture.extend("optional", function() {
         if (!("embind_test_return_optional_int" in cm)) {
             return;

test/embind/embind_test.cpp

@@ -885,6 +885,15 @@ std::map<std::string, int> embind_test_get_string_int_map() {
   return m;
 };
 
+std::map<int, std::string, std::greater<int>> embind_test_get_int_string_greater_map() {
+    std::map<int, std::string, std::greater<int>> m;
+
+    m[1] = "one";
+    m[2] = "two";
+
+    return m;
+}
+
 struct Vector {
   Vector() = delete;
 
@@ -2373,6 +2382,9 @@ EMSCRIPTEN_BINDINGS(tests) {
 
   register_map<std::string, int>("StringIntMap");
   function("embind_test_get_string_int_map", embind_test_get_string_int_map);
+    
+  register_map<int, std::string, std::greater<int>>("IntStringMapGreater");
+  function("embind_test_get_int_string_greater_map", embind_test_get_int_string_greater_map);
 
   function("embind_test_getglobal", &embind_test_getglobal);