Replace name attribute with setters and getters in the C API of mjSpec.

PiperOrigin-RevId: 778816015
Change-Id: Ieffb7a5bce37e887ff009f9a02d2434435e79ca1

src/user/user_api.cc

@@ -1341,6 +1341,19 @@ mjsPlugin* mjs_asPlugin(mjsElement* element) {
 
 
 
+// set element name
+void mjs_setName(mjsElement* element, const char* name) {
+  if (element->elemtype == mjOBJ_DEFAULT) {
+    mjCDef* def = static_cast<mjCDef*>(element);
+    def->name = std::string(name);
+    return;
+  }
+  mjCBase* baseC = static_cast<mjCBase*>(element);
+  baseC->name = std::string(name);
+}
+
+
+
 // copy buffer to destination buffer
 void mjs_setBuffer(mjByteVec* dest, const void* array, int size) {
   const std::byte* buffer = static_cast<const std::byte*>(array);
@@ -1430,6 +1443,16 @@ void mjs_setDouble(mjDoubleVec* dest, const double* array, int size) {
 
 
 
+// get name
+mjString* mjs_getName(mjsElement* element) {
+  if (element->elemtype == mjOBJ_DEFAULT) {
+    return &(static_cast<mjCDef*>(element)->name);
+  }
+  return &(static_cast<mjCBase*>(element)->name);
+}
+
+
+
 // get string
 const char* mjs_getString(const mjString* source) {
   return source->c_str();