[Cake] Find usages returns usages from loaded files when not requested.

[bjorkstromm]

/findusages set with OnlyThisFile: true in request still returns usages from files included via #load directive. Side effects of this can be seen in image below (see highlighting):

Request:

{
  "Type": "request",
  "Seq": 339,
  "Command": "/findusages",
  "Arguments": {
    "FileName": "c:\\Users\\mb\\src\\tmp\\test\\includederror.cake",
    "Line": 18,
    "Column": 11,
    "OnlyThisFile": true,
    "ExcludeDefinition": false
  }
}

Response:

{
  "Request_seq": 339,
  "Command": "/findusages",
  "Running": true,
  "Success": true,
  "Message": null,
  "Body": {
    "QuickFixes": [
      {
        "FileName": "B3437BF2-8AE3-4281-8726-B926BB9DF75D",
        "Line": 8039,
        "Column": 13,
        "EndLine": 8039,
        "EndColumn": 24,
        "Text": "public void Information(System.String value)",
        "Projects": [
          "includederror.cake"
        ]
      },
      {
        "FileName": "c:\\Users\\mb\\src\\tmp\\test\\error.cake",
        "Line": 5,
        "Column": 1,
        "EndLine": 5,
        "EndColumn": 12,
        "Text": "Information(\"Running tasks...\");",
        "Projects": [
          "includederror.cake"
        ]
      },
      {
        "FileName": "c:\\Users\\mb\\src\\tmp\\test\\error.cake",
        "Line": 7,
        "Column": 1,
        "EndLine": 7,
        "EndColumn": 12,
        "Text": "Information(\"Running tasks...\");",
        "Projects": [
          "includederror.cake"
        ]
      },
      {
        "FileName": "c:\\Users\\mb\\src\\tmp\\test\\includederror.cake",
        "Line": 18,
        "Column": 4,
        "EndLine": 18,
        "EndColumn": 15,
        "Text": "Information(\"Running tasks...\");",
        "Projects": [
          "includederror.cake"
        ]
      },
      {
        "FileName": "c:\\Users\\mb\\src\\tmp\\test\\includederror.cake",
        "Line": 24,
        "Column": 4,
        "EndLine": 24,
        "EndColumn": 15,
        "Text": "Information(\"Finished running tasks.\");",
        "Projects": [
          "includederror.cake"
        ]
      },
      {
        "FileName": "c:\\Users\\mb\\src\\tmp\\test\\includederror.cake",
        "Line": 33,
        "Column": 4,
        "EndLine": 33,
        "EndColumn": 15,
        "Text": "Information(\"Hello Cake!\");",
        "Projects": [
          "includederror.cake"
        ]
      }
    ]
  },
  "Seq": 508,
  "Type": "response"
}