Support the new fbtee format

[cpojer]

Hello Crowdin folks,

fbtee is a modern rewrite of Facebook's fbt. It used to work fine with Crowdin until recently, but the file format of source_strings.json was slightly changed:

Before:

{
      "hashToLeaf": {
        "a3ruXfPRZE9V0OoG50TZsA==": {
          "desc": "In the phrase: \"An internationalization framework for JavaScript & React designed to be {=powerful}, {=flexible}, and {=intuitive}.\"",
          "text": "intuitive"
        }
      },
      "filepath": "src/App.tsx",
      "col_beg": 14,
      "col_end": 76
      "line_beg": 164,
      "line_end": 164,
      "project": "",
      "jsfbt": {
        "m": [],
        "t": {
          "desc": "In the phrase: \"An internationalization framework for JavaScript & React designed to be {=powerful}, {=flexible}, and {=intuitive}.\"",
          "text": "intuitive"
        }
      }
    },

After:

{
      "hashToLeaf": {
        "a3ruXfPRZE9V0OoG50TZsA==": {
          "desc": "In the phrase: \"An internationalization framework for JavaScript & React designed to be {=powerful}, {=flexible}, and {=intuitive}.\"",
          "text": "intuitive"
        }
      },
      "filename": "src/App.tsx",
      "loc": {
        "start": {
          "line": 164,
          "column": 14,
          "index": 5838
        },
        "end": {
          "line": 164,
          "column": 76,
          "index": 5900
        }
      },
      "project": "",
      "jsfbt": {
        "m": [],
        "t": {
          "desc": "In the phrase: \"An internationalization framework for JavaScript & React designed to be {=powerful}, {=flexible}, and {=intuitive}.\"",
          "text": "intuitive"
        }
      }
    },

The difference is the new loc prob for location information, and filepath was changed to filename. Would you be able to support the new format?