[MOD][18.0] hr_employee_language: languages selection

[mymage]

As in #1486
Changes the source of language list moving it from the res.lang.csv file to res.lang model.
In this way if you add a language at runtime it will be immediately available.

Added _compute_display_name (ex name_get) to show language name instead language code on selection or m2o widget

[mymage]

@dreispt @primes2h @TheMule71 plase review.
Little differences from #1512

[mymage]

@dreispt Thanks for your notes; I'm not so skilled on coding so your suggestion is very appreciated. I'll give a look asap.

[mymage]

@dreispt Thanks to your comments I refactored the code. The only "strange" thing that I made is this:
self_data = self.env["hr.employee.language"].search([]) for record in self_data:
to have CodeCov at 100%: this because despite I create an element in hr.employee.language for test, here self is empty.

[mymage]

@dreispt @primes2h @TheMule71 ping. Thanks

[mymage]

@dreispt @primes2h @TheMule71 ping. Thanks

[alexey-pelykh]

Thanks for improving the language selection to use res.lang records. A couple of things to address:

1. _compute_display_name() searches ALL hr.employee.language records (self.env["hr.employee.language"].search([])) instead of iterating over self. This is both a performance issue and semantically incorrect — compute methods should only set values on self records.

2. The compute method returns a list of tuples, but Odoo compute methods don't use return values — they assign to self.display_name (which you do, but the return is dead code).

3. Using _() on selection keys (_("%(code)s", code=lang.code)) translates the code itself, which shouldn't be translated — codes are stable identifiers.

Happy to re-review once updated.

[mymage]

Thanks @alexey-pelykh for your suggestions. I updated the code, I hope in the right way.
If this is ok I will fix the other two.