Improve Orientation transform to use the "space" (LPS vs RAS) of a metatensor by default

[CPBridge]

Fix for #8467

Description

As detailed in #8467, the Orientation transform currently always assumes a tensor's affine matrix is in RAS, regardless of the meta["space"] attribute, leading to incorrect performance for LPS metatensors unless the labels are explicitly defined by the user (and it is not at all clear that this needs to be done or how it should be done).

The code in this PR checks whether the input tensor is a metatensor with its affine defined in LPS space. If so, it adjusts the labels passed to nibabel.orientations.axcodes2ornt to give the expected behaviour for LPS tensors.

The default value of the labels parameter of the Orientation transform (and OrientationD) has changed from (('L', 'R'), ('P', 'A'), ('I', 'S')) to None. However, since the behaviour of nibabel.orientations.axcodes2ornt when passed labels=None is equivalent to when passing labels=(('L', 'R'), ('P', 'A'), ('I', 'S')), I would not consider this a breaking change.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[CPBridge]

This is now ready for review