XLF file not processed

Hello,

I'm facing some issue where .xlf files are not processed even if the readme indicated this format is handled 👍
https://www.mojito.global//docs/refs/mojito-file-formats/

`mojito repo-create -n MyRepo -l fr-FR`

```
Create repository: MyRepo
Extracting locale: fr-FR
Extracted RepositoryLocale:
-- bcp47Tag = fr-FR
-- isFullyTranslated = true

created --> repository id: 14
```

```
mkdir MyRepo
cd MyRepo
ls
resources_fr-FR.xlf
```

`mojito import -r MyRepo`

```
Start importing localized files for repository: MyRepo

Finished
```

Nothing got imported.
I had to rename .xlf to .xliff file to be detected.
.xlf should also be handled.

Start by reproducing the report with the documented XLF format and the `mojito import -r MyRepo` command, then inspect the import format detection used by the repository importer. Compare processing of `.xlf` and `.xliff`; done means an `.xlf` file is detected and imported without renaming it.

Written by the indexing model from the issue text.