Add filterexact and actearly options to MuJoCo.

When filterexact is a new dyntype which is just like the existing `filter`, but the activation state is integrated with exact integration, instead of simple Euler integration.

When actearly is specified on a general actuator, `qfrc_actuator` is computed using the next timestep's `act` value, instead of the current value.

PiperOrigin-RevId: 554438423
Change-Id: I30759bb754239f2c6e2250b2d65351a5ec633310

Author: nimrod-gileadi

dm_control/mjcf/schema.xml

@@ -394,12 +394,13 @@
             <attribute name="gear" type="array" array_type="float" array_size="6"/>
             <attribute name="cranklength" type="float"/>
             <attribute name="user" type="array" array_type="float"/>
-            <attribute name="dyntype" type="keyword" valid_values="none integrator filter muscle user"/>
+            <attribute name="dyntype" type="keyword" valid_values="none integrator filter filterexact muscle user"/>
             <attribute name="gaintype" type="keyword" valid_values="fixed affine muscle user"/>
             <attribute name="biastype" type="keyword" valid_values="none affine muscle user"/>
             <attribute name="dynprm" type="array" array_type="float" array_size="10"/>
             <attribute name="gainprm" type="array" array_type="float" array_size="10"/>
             <attribute name="biasprm" type="array" array_type="float" array_size="10"/>
+            <attribute name="actearly" type="keyword" valid_values="false true"/>
           </attributes>
         </element>
         <element name="motor">
@@ -690,12 +691,13 @@
                 <attribute name="cranklength" type="float"/>
                 <attribute name="user" type="array" array_type="float"/>
                 <attribute name="actdim" type="int"/>
-                <attribute name="dyntype" type="keyword" valid_values="none integrator filter muscle user"/>
+                <attribute name="dyntype" type="keyword" valid_values="none integrator filter filterexact muscle user"/>
                 <attribute name="gaintype" type="keyword" valid_values="fixed affine muscle user"/>
                 <attribute name="biastype" type="keyword" valid_values="none affine muscle user"/>
                 <attribute name="dynprm" type="array" array_type="float" array_size="10"/>
                 <attribute name="gainprm" type="array" array_type="float" array_size="10"/>
                 <attribute name="biasprm" type="array" array_type="float" array_size="10"/>
+                <attribute name="actearly" type="keyword" valid_values="false true"/>
               </attributes>
             </element>
             <element name="motor">
@@ -1602,12 +1604,13 @@
             <attribute name="cranksite" type="reference" reference_namespace="site"/>
             <attribute name="slidersite" type="reference" reference_namespace="site"/>
             <attribute name="user" type="array" array_type="float"/>
-            <attribute name="dyntype" type="keyword" valid_values="none integrator filter muscle user"/>
+            <attribute name="dyntype" type="keyword" valid_values="none integrator filter filterexact muscle user"/>
             <attribute name="gaintype" type="keyword" valid_values="fixed affine muscle user"/>
             <attribute name="biastype" type="keyword" valid_values="none affine muscle user"/>
             <attribute name="dynprm" type="array" array_type="float" array_size="10"/>
             <attribute name="gainprm" type="array" array_type="float" array_size="10"/>
             <attribute name="biasprm" type="array" array_type="float" array_size="10"/>
+            <attribute name="actearly" type="keyword" valid_values="false true"/>
           </attributes>
         </element>
         <element name="motor" repeated="true" namespace="actuator">