Add test and example config for DeepSetsPolicy

config/networks.json5

@@ -0,0 +1,34 @@
+{
+    ego_state: {
+        input_dim: 5, // number of state vars
+        hidden_n: 1,
+        hidden_dim: 5,
+        output_dim: 5
+    },
+    deepsets: {
+        input_dim: 5, // number of relative state vars for others
+        phi: {
+            hidden_n: 1,
+            hidden_dim: 20,
+        },
+        latent_dim: 20,
+        rho: {
+            hidden_n: 1,
+            hidden_dim: 10,
+        },
+        output_dim: 10
+    },
+    path_encoder: {
+        input_dim: 40, // 2 * path length for (x,y) coordinates
+        hidden_n: 2,
+        hidden_dim: 20,
+        output_dim: 10,
+    },
+    head: {
+        input_dim: 0, // computed in policy constructor
+        hidden_n: 1,
+        hidden_dim: 50,
+        output_dim: 1, // number of outputs e.g. number of actions, or just one
+        final_activation: 'sigmoid',
+    }
+}