use FEPE::get_normal_vector() to be consistent with FEE

[jh66637]

As discussed in #15302 I am renaming FEPE::get_normal_vector() to be consistent with FEE

@bergbauer @kronbichler

[peterrum]

Are there no tests?

[jh66637]

I didn't find one. Let's wait if the pipeline fails, but I am pretty confident :)

[kronbichler]

Given #15302, we should wait to see what the consensus is on the general names.

[jh66637]

As discussed in #15302 I early-deprecated get_normal_vector() in favor of normal_vector(). To ensure user code does not break, I copied a test which uses get_normal_vector(). This test can be removed when get_normal_vector() is eventually completely removed.

@bangerth @kronbichler @peterrum @bergbauer

[kronbichler]

I agree. However, can we wait with marking it as early deprecation until after the release? My point is that we will have a release in a few weeks, so deprecation warnings start essentially immediately for someone working with master. Since this is an interface used in many places, I would prefer to delay the cycle by one year. This means the feature will get deprecated in summer 2024 and removed in 2025, which is more feasible than 2023 and 2024 in my opinion.

[kronbichler]

And by the way, thank you for the effort, it seems you found all cases I could think about.

[jh66637]

@kronbichler I removed the deprecation attribute but kept the rest as is. We can keep #15302 open, so we don't forget to add the attribute after the release.

[kronbichler]

Any additional comments? If not, I suggest to merge this PR in a day or so.