Spl2 fixes

[fantavlik]

• Provide better error handling and configurability for language server download and install by allowing user to specify custom path to LSP file

• Fix issue with progress bars getting stuck

• Allow users to input earliest and latest times Demo:

• Serialize the format for SPL2 notebooks saved to disk to more closely match modules.json expectations, example:

  {
  "modules": [
  {
    "name": "module1",
    "namespace": "",
    "definition": "$q1 = from _internal where log_level != \"ERROR\"",
    "_vscode": {
      "metadata": {
        "splunk": {
          "earliestTime": "-24h",
          "latestTime": "now"
        }
      },
      "outputs": []
    }
  },
  {
    "name": "module2",
    "namespace": "",
    "definition": " $q2 = from main",
    "_vscode": {
      "metadata": {
        "splunk": {
          "earliestTime": "@d",
          "latestTime": "now"
        }
      },
      "outputs": []
    }
  }
  ],
  "app": "apps.search"
  }