Add languages to SDK

[Sevitas]

Motivation

Feature is required thus, no method providing project languages is present. User can now get all his project languages.

Proposed solution

Introduce a method providing all project languages

Additional context

Should be released 01.25.2021
endpoint-{deliveryApi}/{projectId}/languages

`{
  "languages": [
    {
      "system": {
        "id": "00000000-0000-0000-0000-000000000000",
        "name": "Default project language",
        "codename": "default"
      }
    },
    {
      "system": {
        "id": "8fab3c4c-2ba4-47a9-8e53-df8e6154054f",
        "name": "First Lanugage",
        "codename": "first_language"
      }
    },
    {
      "system": {
        "id": "24d5aaa6-a0db-4e20-8c11-6eb272bbe168",
        "name": "Second Language",
        "codename": "second_language"
      }
    }
  ],
  "pagination": {
    "skip": 0,
    "limit": 0,
    "count": 3,
    "next_page": ""
  }
}`