Proposal: Display Greek Language/Locale Option as 'Greek' Instead of ISO 639-1 Name

### Problem

Both the locale plugin in Switchboard and the operating system installer in Elementary OS currently display the Greek language option using its default ISO 639-1 code name. This appears as 'Greek, Modern (1453-)' in the locale plugin and 'Modern Greek (1453-)' in the installer. While this might be useful in a linguistic context (mainly to differentiate Modern Greek from Ancient Greek), it feels verbose and confusing within a language selection menu, as Ancient Greek support is doubtful in an operating system, making this distinction unnecessary and potentially misleading for users. Furthermore, sorting 'Modern Greek (1453-)' with the letter 'M' in the installer rather than 'G' can make it harder for Greek-speaking users to locate their preferred language.


Note: [This proposal has also been submitted to the Locale Plug for Switchboard repository for consideration.](https://github.com/elementary/switchboard-plug-locale/issues/223)

### Proposal

I propose changing the Greek language option from its current ISO 639-1 name to simply 'Greek' to improve user interface clarity and help Greek-speaking users easily find and select their language.

EDIT: Looking at the screenshot and the installer, I noticed the other languages listed with their native names. Due to consistency, I believe that the best-fitting replacement would be 'Ελληνικά'. The switchboard plug already lists Greek as such.