Add mju_clip, mju_fill, mju_eye and mju_symmetrize to python bindings.

- Also change signatures of `mju_fill` and `mju_symmetrize` to conform to standard.

PiperOrigin-RevId: 485613824
Change-Id: I8dd618bac92ef40aa6c76380fa73302e81968687

introspect/functions.py

@@ -5295,14 +5295,14 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                      inner_type=ValueType(name='mjtNum'),
                  ),
              ),
-             FunctionParameterDecl(
-                 name='n',
-                 type=ValueType(name='int'),
-             ),
              FunctionParameterDecl(
                  name='val',
                  type=ValueType(name='mjtNum'),
              ),
+             FunctionParameterDecl(
+                 name='n',
+                 type=ValueType(name='int'),
+             ),
          ),
          doc='Set res = val.',
      )),
@@ -5756,17 +5756,23 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          return_type=ValueType(name='void'),
          parameters=(
              FunctionParameterDecl(
-                 name='mat',
+                 name='res',
                  type=PointerType(
                      inner_type=ValueType(name='mjtNum'),
                  ),
              ),
+             FunctionParameterDecl(
+                 name='mat',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjtNum', is_const=True),
+                 ),
+             ),
              FunctionParameterDecl(
                  name='n',
                  type=ValueType(name='int'),
              ),
          ),
-         doc="Symmetrize square matrix M = (M + M')/2.",
+         doc="Symmetrize square matrix res = (mat + mat')/2.",
      )),
     ('mju_eye',
      FunctionDecl(