Additional groove joint 2D implementation with DOF: 1 translation + 1 rotation

[legendofa]

Implements additional GrooveJoint from to issue: #772
The joint is currently only implemented for 2d behind the feature flag "dim2".

I tested this so far with this adjusted example, my plan is to implement a more elaborate example for more testing:

use rapier2d::prelude::*;
use rapier_testbed2d::Testbed;

pub fn init_world(testbed: &mut Testbed) {
    /*
     * World
     */
    let mut bodies = RigidBodySet::new();
    let mut colliders = ColliderSet::new();
    let mut impulse_joints = ImpulseJointSet::new();
    let multibody_joints = MultibodyJointSet::new();

    /*
     * Ground
     */
    let ground_size = 0.75;
    let ground_height = 0.1;

    let rigid_body = RigidBodyBuilder::fixed().translation(vector![0.0, -ground_height]);
    let floor_handle = bodies.insert(rigid_body);
    let collider = ColliderBuilder::cuboid(ground_size, ground_height);
    colliders.insert_with_parent(collider, floor_handle, &mut bodies);

    let rigid_body =
        RigidBodyBuilder::fixed().translation(vector![-ground_size - ground_height, ground_size]);
    let floor_handle = bodies.insert(rigid_body);
    let collider = ColliderBuilder::cuboid(ground_height, ground_size);
    colliders.insert_with_parent(collider, floor_handle, &mut bodies);

    let rigid_body =
        RigidBodyBuilder::fixed().translation(vector![ground_size + ground_height, ground_size]);
    let floor_handle = bodies.insert(rigid_body);
    let collider = ColliderBuilder::cuboid(ground_height, ground_size);
    colliders.insert_with_parent(collider, floor_handle, &mut bodies);

    /*
     * Character we will control manually.
     */
    let rigid_body = RigidBodyBuilder::kinematic_position_based().translation(vector![0.0, 0.3]);
    let character_handle = bodies.insert(rigid_body);
    let collider = ColliderBuilder::cuboid(0.15, 0.3);
    colliders.insert_with_parent(collider, character_handle, &mut bodies);

    /*
     * Tethered cube.
     */
    let rad = 0.04;

    let rigid_body = RigidBodyBuilder::new(RigidBodyType::Dynamic).translation(vector![1.0, 1.0]);
    let child_handle = bodies.insert(rigid_body);
    let collider = ColliderBuilder::cuboid(rad, rad);
    colliders.insert_with_parent(collider, child_handle, &mut bodies);

    let axis = UnitVector::new_normalize(vector![1.0, 1.0]);
    let prismatic_joint = GrooveJointBuilder::new(axis)
        .local_anchor1(point![0.0, 0.0])
        .local_anchor2(point![0.0, 0.0])
        .build();
    impulse_joints.insert(character_handle, child_handle, prismatic_joint, true);

    /*
     * Set up the testbed.
     */
    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
    testbed.set_character_body(character_handle);
    testbed.look_at(point![0.0, 1.0], 100.0);
}

If there is anything that i have overlooked, let me know :)
This is still a draft as i think this needs a bit more testing.