When path is empty do not replace string

[eddynaka]

This change will fix the following exception:

ArgumentException: String cannot be of zero length. (Parameter 'oldValue')
at System.String.Replace(String oldValue, String newValue)
at Microsoft.CodeAnalysis.IL.Sdk.CompilerDataLogger..ctor(IAnalysisContext analysisContext, IEnumerable`1 targetFileSpecifiers) in D:\a\r1\a\src\BinSkim.Sdk\CompilerDataLogger.cs:line 59
at Microsoft.CodeAnalysis.IL.AnalyzeCommand.CreateContext(AnalyzeOptions options, IAnalysisLogger logger, RuntimeConditions runtimeErrors, PropertiesDictionary policy, String filePath) in D:\a\r1\a\src\BinSkim.Driver\AnalyzeCommand.cs:line 59
at Microsoft.CodeAnalysis.Sarif.Driver.AnalyzeCommandBase`2.DetermineApplicabilityAndAnalyze(TOptions options, IEnumerable`1 skimmers, TContext rootContext, String target, ISet`1 disabledSkimmers)
at Microsoft.CodeAnalysis.Sarif.Driver.AnalyzeCommandBase`2.AnalyzeTargets(TOptions options, IEnumerable`1 skimmers, TContext rootContext, IEnumerable`1 targets)
at Microsoft.CodeAnalysis.Sarif.Driver.AnalyzeCommandBase`2.Analyze(TOptions options, AggregatingLogger logger)
at Microsoft.CodeAnalysis.Sarif.Driver.AnalyzeCommandBase`2.Run(TOptions options