ts-lce fails when tsconfig.json contains a path reference to a file

[JohT]

According to the Typescript documentation, it is also possible to specify files as path references in the tsconfig.json configuration:

{
  "references": [
    { "path": "./tsconfig.ui.json" }
  ]
}

In that case, ts-lce fails with an error message like this:

ENOTDIR: not a directory, open '.../jqassistant-typescript-plugin/typescript/test/core/integration/sample-projects/path-references/tsconfig.ui.json/tsconfig.json'

      102 |     private static parseTsConfig(projectRoot: string): ParsedCommandLine {
      103 |         const tsConfigPath = path.join(projectRoot, "tsconfig.json");
    > 104 |         const configFileText = fs.readFileSync(tsConfigPath, 'utf8');
          |                                   ^
      105 |         const configFileSourceFile = createSourceFile(
      106 |             'tsconfig.json', configFileText, ScriptTarget.JSON
      107 |         );

      at Function.parseTsConfig (src/core/utils/project.utils.ts:104:35)
      at Function.getProjectInfo (src/core/utils/project.utils.ts:74:31)
      at Function.getProjectInfo (src/core/utils/project.utils.ts:80:46)
      at Function.determineProjects (src/core/utils/project.utils.ts:46:37)
      at Object.<anonymous> (test/core/integration/path-references.test.ts:9:49)

Reproducer: #126

If contributions are welcome I could give It a try of course in sync with you discussing/reviewing my pull request.