feat: Conditionally save fit files into GH action output

[anlesk]

Prompted by: #526 (comment)

Saves the fit files as GH action artifacts

[adepue]

This seems to cause an invalid config json file if you don't explicitly set save Local to true, as it omits the variable false. This error happened to me when running via GH Actions

 },
    "Format": {
      "Fit": true,
      "Json": false,
      "Tcx": false,
      "SaveLocalCopy": ,
      "IncludeTimeInHRZones": false,
      "IncludeTimeInPowerZones": false,
      "DeviceInfoPath": "./deviceInfo.xml"
    },
    "Peloton": {

Additionally, once setting to true, the output fails to save with a path character error:

Artifact path is not valid: /c46871a40e964879bf32d9c7055d7786_Extra_10:_Low_Impact_Ride_with_Matt_Wilpers.fit. Contains the following character: Colon : Invalid characters include: Double quote 

Haven't had a chance to look into it further yet, but noting here incase anyone happens to run into it or has immediate ideas.