Github clickhouse queries improvements

[IvanIvanoff]

Changes

• Add proper zero filling for projects that have github organizations that are not producing any public events. Previously this would return an empty list.
• Fix internal server error when aggregatedTimeseriesData was invoked on project with no github organization and return null.
• Replace null with 0 in the aggregatedTimeseriesData when the project has github organization but no events.

{
  getMetric(metric: "dev_activity") {
    tet: aggregatedTimeseriesData(slug: "tether", from: "utc_now-30d", to: "utc_now") 
    san: aggregatedTimeseriesData(slug: "santiment", from: "utc_now-30d", to: "utc_now") 
    eth: aggregatedTimeseriesData(slug: "ethereum", from: "utc_now-30d", to: "utc_now") 
    mkr: aggregatedTimeseriesData(slug: "maker", from: "utc_now-30d", to: "utc_now") 
  }
}

{
  "data": {
    "getMetric": {
      "eth": 8424,
      "mkr": null,
      "san": 1229,
      "tet": 0
    }
  }
}

Ticket

Checklist:

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have tried to find clearer solution before commenting hard-to-understand parts of code
• I have added tests that prove my fix is effective or that my feature works