CSV import : ability to increase field size

### Describe the problem

We are trying to import our translations from csv files but we have an error saying some fields are exceeding 131072 char limit.
```
Could not parse translation base file: field larger than field limit (131072)
```

After digging the web it seems that this limit can be increased (it is a configuration arg of the csv reader).
It would be great to be able to increase it with an env var.

### Solution brainstorm

An Env var to set field size limit

### Describe alternatives you have considered

_No response_

### Screenshots

_No response_

### Additional context

_No response_

Find the CSV import entry point and the CSV reader configuration, then trace how translation base files are parsed. Add the requested environment-variable configuration for the field-size limit and verify that imports with fields larger than 131072 characters succeed without breaking normal CSV imports.

Written by the indexing model from the issue text.