[tests] Migrate formatter tests to file-based cases

* Replace `FormatterTest` and `GoogleStyleFormatterKtTest` with
file-based cases under cases/
* Move parse-error tests from `FormatterTest` to `ParserTest`

Author: AbdullinAM

core/src/test/kotlin/org/jetbrains/ktfmt/format/FormatTest.kt

@@ -0,0 +1,19 @@
+package org.jetbrains.ktfmt.format
+
+import org.jetbrains.ktfmt.testutil.FormatterTestFactory
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+// core/src/test/resources/cases/format
+class FormatTest : FormatterTestFactory() {
+  @Test
+  fun `preserve LF, CRLF and CR line endings`() {
+    val lines = listOf("fun main() {", "  println(\"test\")", "}")
+    for (ending in listOf("\n", "\r\n", "\r")) {
+      val code = lines.joinToString(ending, postfix = ending)
+
+      val reformatted = Formatter.format(DEFAULT_CASE_FORMAT, code)
+      assertEquals(code, reformatted)
+    }
+  }
+}