Update v2 language endpoint to add default language property

[fmontes]

As a FE developer I need to know which language is default to implement multilanguage SPAa

Describe the solution you'd like

In the endpoint /api/v2/languages response we have:

{
    "entity": [
        {
            "country": "United States",
            "countryCode": "US",
            "id": 1,
            "language": "English",
            "languageCode": "en"
        },
        {
            "country": "Espana",
            "countryCode": "ES",
            "id": 2,
            "language": "Espanol",
            "languageCode": "es"
        }
    ],
    "errors": [],
    "i18nMessagesMap": {},
    "messages": [],
    "permissions": []
}

The idea is to add the default like:

        {
            "country": "United States",
            "countryCode": "US",
            "id": 1,
            "language": "English",
            "languageCode": "en",
            "default": true,
        },
 ...

Acceptance Criteria

1. Update endpoint to get the default language property
2. Work in all the supported browsers (don't forget IE11 and iPad)
3. Multilanguage
4. Unit test

[erickgonzalez]

PR: #19013

[erickgonzalez]

E.g. how the JSON will look:

"country": "United States",
            "countryCode": "US",
            "defaultLanguage": true,
            "id": 1,
            "language": "English",
            "languageCode": "en"

[bryanboza]

Fixed, tested on release-5.3.7 // Postgres. Need card added in order to allow change this value from UI