Mention the actual missing path in exception output when SourceRootTranslator constructor fails. (#990)

Mention the actual missing path in exception output when SourceRootTranslator constructor fails.

Author: markusschaber

src/coverlet.core/Helpers/SourceRootTranslator.cs

@@ -38,7 +38,7 @@ public SourceRootTranslator(string moduleTestPath, ILogger logger, IFileSystem f
             }
             if (!_fileSystem.Exists(moduleTestPath))
             {
-                throw new FileNotFoundException("Module test path not found", moduleTestPath);
+                throw new FileNotFoundException($"Module test path '{moduleTestPath}' not found", moduleTestPath);
             }
             _sourceRootMapping = LoadSourceRootMapping(Path.GetDirectoryName(moduleTestPath));
         }