Fix non-localized company suffixes in CH and it locales

[huerlisi]

Motivation / Background

Faker::Company.name produced anglophone legal forms that do not exist in
these locales:

Faker::Config.locale = 'de-CH'
Faker::Company.name  #=> "Klimczak LLC"

Faker::Config.locale = 'fr-CH'
Faker::Company.name  #=> "Adam LLC"

Faker::Config.locale = 'it'
Faker::Company.name  #=> "Russo-Russo Group"

LLC and Inc. are US forms and are not used in Switzerland; Group is
English. This Pull Request fixes the company suffix lists:

• de-CH: drop the English LLC and Inc. suffixes.
• fr-CH: drop LLC/Inc. and add the Swiss-French forms SA and Sàrl.
• it: replace English Group with the Italian Gruppo.

Additional information

Output after the change:

Faker::Config.locale = 'de-CH'
Faker::Company.name  #=> "Slotta AG"

Faker::Config.locale = 'fr-CH'
Faker::Company.name  #=> "Dumas, Bénoit et Duval"   # also: "Morin SA", "Brun Sàrl"

Faker::Config.locale = 'it'
Faker::Company.name  #=> "Monti, Cattaneo e Costantin Gruppo"

Tests assert the English forms are gone (and the localized forms present)
so the lists don't regress.

Checklist

• This Pull Request is related to one change.
• Commit message has a detailed description of what changed and why.
• Tests are added or updated.
• Tests and Rubocop are passing before submitting your proposed changes.

[huerlisi]

I used Claude Code to create this MR and it included very specific unit tests. I don't see too much value in those but they don't hurt.

Should I drop them, or what is best practice in this repo around unit tests?

[huerlisi]

Related but not directly part of this MR: I understand that the project has a "freeze" on new locales. For Switzerland there's currently DE and FR locales available, but no for the IT speaking part. As Swiss that feels as kind of a bug:-)

Would you accept a contribution that introduces an it-CH locale?