externalize `files` information to different file

[Ginxo]

caused by: #44

after #44 the data/latest.json file has increased size, I recommend to externalize files object to different file (something like files-latest.json and the one by date).
The get files-latest.json mechanism will be perform once latest data is already loaded, just consider branch comparison as a secondary functionallity

I would recommend to solve this issue before #29

[lampajr]

I propose to generate a new file files-latest.json having a structure like this one:

{
  "metadata": {
    ...
  },
  "branchesComparison": {
    "7.67.x": {
      "main": {
        "owner/project1": ["sha11", "sha12"],
        "owner/project2": ["sha21", "sha22"],
        ...
      },
      "7.67.x-blue": {
        "owner/project1": ["sha13", "sha14"],
        "owner/project2": ["sha23", "sha24"],
        ...
      }
    },
    "7.67.x-blue": {
      "main": {
        "owner/project1": ["sha15", "sha16"],
        "owner/project2": ["sha25", "sha26"],
        ...
      },
      "7.67.x": {
        "owner/project1": ["sha13", "sha14"],
        "owner/project2": ["sha23", "sha24"],
        ...
      }
    },
    ...
  },
  "files": {
    "sha11": {
      "filename": "",
      "blob_url": "",
      "content_url": ""
    },
    "sha12": {
      "filename": "",
      "blob_url": "",
      "content_url": ""
    },
    ...
  }
}

• metadata: contains additional information, if needed.
• files: contains files information, like its name. Files are uniquely identified by their sha.
• branchesComparison: provide all project's different files given base and head branches to compare. The tree structure is accessible starting from the branches itself.

@Ginxo wdyt?

[Ginxo]

thanks @lampajr