Add physics solver settings to project settings

Helps with discovery and setup of physics solver settings, in a specific
project settings section for both 2D and 3D.

Other changes for cleanup:
-Removed unused space parameters in 3D
SPACE_PARAM_BODY_ANGULAR_VELOCITY_DAMP_RATIO
SPACE_PARAM_CONSTRAINT_DEFAULT_BIAS
-Added custom solver bias for Shape3D (same as Shape2D)
-Improved documentation for solver settings

servers/physics_server_3d.h

@@ -268,8 +268,6 @@ public:
 		SPACE_PARAM_BODY_LINEAR_VELOCITY_SLEEP_THRESHOLD,
 		SPACE_PARAM_BODY_ANGULAR_VELOCITY_SLEEP_THRESHOLD,
 		SPACE_PARAM_BODY_TIME_TO_SLEEP,
-		SPACE_PARAM_BODY_ANGULAR_VELOCITY_DAMP_RATIO,
-		SPACE_PARAM_CONSTRAINT_DEFAULT_BIAS,
 		SPACE_PARAM_SOLVER_ITERATIONS,
 	};