Codelist improvements

### Description

Codelists on Altinn 2 differs slightly from how it's implementet on Altinn 3.

**Altinn 3**
Current codelist implementation can be either dynamic based on code or static based on json files. Either way they both return the same datamodel:

* Value (The value to be stored)
* ValueType (String, Number, Boolean, Null=ValueType not set)
* Label (The text to display to the user, either directly or as a reference to a language resource)
* Description (A text to further detail what this entry should be used for)
* HelpText (A text to be used as a mouse over tooltip)

**Altinn 2**
This is a bit different that what was the case for Altinn 2:
* Title (The text to display to the user in the provided language, same as Label with the exception on how language is handled)
* Code (The value to be stored, same as Value)
* Language (The language code for the specified code/title)
* Value1 (An optional value that can be configured to use instead of code)
* Value2 (An optional value that can be configured to use instead of code)
* Value3 (An optional value that can be configured to use instead of code)

**Differences**
* In Altinn 3 you need to go via the language resource files, while in Altinn 2 you can specifiy the language directly.
* In Altinn 2 you have 3 alternative values that not only can be used to store, but also that can be used for grouping/sorting/filtering
* In Altinn 2 there is also the ability to support maintenace via an Excel spreadsheet that can be exported and imported back
* In Altinn 2 changes to the codelists can be updated without deploying the application, which eases the application maintenance
* In Altinn 2 you had the option of sharing codelists accross both service owners (global) as well as accross applications within a service owner boundary.

### Additional Information

Altinn 2 codelist description can be found here: https://altinn.github.io/docs/tul/funksjonalitet/kodelister/

### Tasks
- [ ] Analyse furter the differences between Altinn 2 and Altinn 3 to see if we can have the same support in a new codelist version in Altinn 3

### Acceptance Criterias

_No response_

Start by reading the Altinn 2 codelist description linked in the issue and reviewing the current Altinn 3 codelist implementation in this repository. Compare the supported data model, language handling, alternative values, Excel maintenance, updates without deployment, and sharing scope; document which differences should be supported in a new codelist version.

Written by the indexing model from the issue text.