Change test storage from List to class in Fix plugin

What's done:
* Change test storage from List to class in plugin
Closes #221

save-plugins/fix-and-warn-plugin/src/commonMain/kotlin/org/cqfn/save/plugins/fixandwarn/FixAndWarnPlugin.kt

@@ -67,7 +67,7 @@ class FixAndWarnPlugin(
  override fun handleFiles(files: Sequence<TestFiles>): Sequence<TestResult> {
  // Need to update private fields after validation
  initOrUpdateConfigs()
- val expectedFiles = files.map { it as FixPlugin.FixTestFiles }.map { it.expected }
+ val expectedFiles = files.map { it as FixPlugin.Test }.map { it.expected }
 
  // Remove (in place) warnings from test files before fix plugin execution
  val filesAndTheirWarningsMap = removeWarningsFromExpectedFiles(expectedFiles)

save-plugins/fix-plugin/src/commonMain/kotlin/org/cqfn/save/plugins/fix/FixPlugin.kt

@@ -50,7 +50,7 @@ class FixPlugin(
  val fixPluginConfig = testConfig.pluginConfigs.filterIsInstance<FixPluginConfig>().single()
  val generalConfig = testConfig.pluginConfigs.filterIsInstance<GeneralConfig>().single()
 
- return files.map { it as FixTestFiles }.chunked(fixPluginConfig.batchSize!!.toInt()).map { chunk ->
+ return files.map { it as Test }.chunked(fixPluginConfig.batchSize!!.toInt()).map { chunk ->
  val pathMap = chunk.map { it.expected to it.test }
  val pathCopyMap = pathMap.map { (expected, test) -> expected to createTestFile(test, generalConfig) }
  val testCopyNames =
@@ -172,19 +172,9 @@ class FixPlugin(
  .toList()
  .joinToString { (type, lines) -> "$type: $lines lines" }
 
- /**
- * @property expected expected file
- */
- interface FixTestFiles : TestFiles {
- /**
- * path to expected file
- */
- val expected: Path
- }
-
  /**
  * @property test test file
  * @property expected expected file
  */
- class Test(override val test: Path, override val expected: Path) : FixTestFiles
+ class Test(override val test: Path, val expected: Path) : TestFiles
 }

save-plugins/fix-plugin/src/commonNonJsTest/kotlin/org/cqfn/save/plugins/fix/FixPluginTest.kt

@@ -171,7 +171,7 @@ class FixPluginTest {
  useInternalRedirections = false
  )
  .discoverTestFiles(tmpDir)
- .map { it as FixPlugin.FixTestFiles }
+ .map { it as FixPlugin.Test }
  .map { it.expected to it.test }
  .toList()
 }