add HasCamelCasing trait to UserGroupStage, UserUserGroup, and InvitationModel models

[taslangraham]

For #10234

[taslangraham]

Ready for review @asmecher

[asmecher]

Thanks, @taslangraham! @defstat, would you mind reviewing this?

[defstat]

@taslangraham thanks, this trait saves so much code and it is super helpful. Can you add the necessary PRs on OJS, OMP, OPS so that the tests run on the pkp-lib PR?

[defstat]

If you need any help with the tests I will be happy to help.

[taslangraham]

@defstat I've added PRs for submodule updates for each app.
I've listed them here in the issue description - #10234

[defstat]

Thanks @taslangraham. Just check one test that has already failed on OMP. It could be a test glitch and could be resolved if you rerun it. But check if this is the case. Other than that I have no comments on the code

[taslangraham]

@defstat all tests are now passing.

[defstat]

Perfect, I have no other comments

[taslangraham]

@defstat I don't have write access. If you do, could you please merge this?

[defstat]

@taslangraham everything merged! Thanks.