Deprecate modelchain.get_orientation

[RDaxini]

• Related discussion Fix typos in ModelChain error messages #2492
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See discussion in related #2492

Original test test_bad_get_orientation(): only checked whether a value error was raised, the new test (with what I think is a clearer name) checks not only whether a value error is raised but also whether the error string matches

[RDaxini]

I could also add tests to check whether the correct values are returned according to the strategy provided, is this necessary?
For example:

def test_get_orientation_flat():
    surface_tilt, surface_azimuth = modelchain.get_orientation('flat')
    assert surface_tilt == 0
    assert surface_azimuth == 180

[cwhanse]

tests to check whether the correct values are returned

Optional IMO. I'm actually wondering why modelchain.py has this function. It was added in 2016 in the initial modelchain build and hasn't been used since in the ModelChain methods. There's a PVSystem.get_orientation method but that looks like just casting to a dict.

[RDaxini]

@cwhanse fair observation, are you proposing we deprecate and remove the function entirely?

[wholmgren]

Yes get rid of it!

[echedey-ls]

LGTM :)
Just a comment and a formatting preference down below.

[echedey-ls]

Strictly following deprecations as a concept, this shouldn't be removed till the removal - a just in case clarification. Anyway, we all are sure this function hasn't found it's way into many codebases so I agree with removing it here.

[echedey-ls]

Suggested change

	0.14.0. (:pull:`2691`)
	``v0.14.0``. (:pull:`2691`)