refactor(cameras): cameras API extension (#2808)

* feat(cameras): add new read_latest() method

* fix(cameras): fix threading bug + clear state

* refactor(cameras): multiple improvements

* feat(camera): add context manager to camera base class

* chore(camera): slight modifications to opencv

* test(cameras): update opencv tests according to the changes

* refactor(cameras): reflect desing changes to realsense + deal with depth

* test(cameras): fix realsense tests accordingly to new changes

* refactor(cameras): update reachymini and zmq accordingly

* chore: wrap resource sensitive examples into a try/finally

* test(cameras): add test for new read_latest

* test(cameras): fix problem with image artifact in opencv tests

* test(cameras): fix test_read_latest_high_frequency expectations

* Apply suggestions from code review 1

Co-authored-by: Caroline Pascal <caroline8.pascal@gmail.com>
Signed-off-by: Steven Palma <imstevenpmwork@ieee.org>

* chore(cameras): address feedback

* feat(cameras): add max_age_ms check in read_latest

* test(cameras): fix read_latest tests

* chore(redundancies): removing redundancies in Reachy 2 camera class

* fix(warmup): replacing the arbitrary time.sleep in by an actual warmup in the RealSense camera class

* chore(format): formatting latest changes

* chore(warning): adding a "to be implemented" warning for read_latest() in Camera base class

* chore(warning): making read_latest() warning message shorter and clearer

---------

Signed-off-by: Steven Palma <imstevenpmwork@ieee.org>
Co-authored-by: Caroline Pascal <caroline8.pascal@gmail.com>

tests/cameras/test_reachy2_camera.py

@@ -150,6 +150,44 @@ def test_async_read_before_connect(camera):
         _ = camera.async_read()
 
 
+def test_read_latest(camera):
+    camera.connect()
+
+    frame = camera.read()
+    latest = camera.read_latest()
+
+    assert isinstance(latest, np.ndarray)
+    assert latest.shape == frame.shape
+
+
+def test_read_latest_before_connect(camera):
+    # camera fixture yields an unconnected camera instance
+    with pytest.raises(DeviceNotConnectedError):
+        _ = camera.read_latest()
+
+
+def test_read_latest_high_frequency(camera):
+    camera.connect()
+
+    # prime to ensure frames are available
+    ref = camera.read()
+
+    for _ in range(20):
+        latest = camera.read_latest()
+        assert isinstance(latest, np.ndarray)
+        assert latest.shape == ref.shape
+
+
+def test_read_latest_too_old(camera):
+    camera.connect()
+
+    # prime to ensure frames are available
+    _ = camera.read()
+
+    with pytest.raises(TimeoutError):
+        _ = camera.read_latest(max_age_ms=0)  # immediately too old
+
+
 def test_wrong_camera_name():
     with pytest.raises(ValueError):
         _ = Reachy2CameraConfig(name="wrong-name", image_type="left")