Kapt: Move line metadata to .kaptMetadata external files (KT-22386)

Placing location table inside .java file triggers annotation processor to run on each line table modification (even when the stub declarations themselves are the same). So we move it to the separate file.

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/KaptIncrementalIT.kt

@@ -160,7 +160,9 @@ abstract class KaptIncrementalBaseIT(val shouldUseStubs: Boolean, val useKapt3:
                 assertFileExists("$kapt3IncDataPath/bar/B.class")
                 assertFileExists("$kapt3IncDataPath/bar/UseBKt.class")
                 assertFileExists("$kapt3StubsPath/bar/B.java")
+                assertFileExists("$kapt3StubsPath/bar/B.kapt_metadata")
                 assertFileExists("$kapt3StubsPath/bar/UseBKt.java")
+                assertFileExists("$kapt3StubsPath/bar/UseBKt.kapt_metadata")
             }
         }
 
@@ -176,7 +178,9 @@ abstract class KaptIncrementalBaseIT(val shouldUseStubs: Boolean, val useKapt3:
                 assertNoSuchFile("$kapt3IncDataPath/bar/B.class")
                 assertNoSuchFile("$kapt3IncDataPath/bar/UseBKt.class")
                 assertNoSuchFile("$kapt3StubsPath/bar/B.java")
+                assertNoSuchFile("$kapt3StubsPath/bar/B.kaptMetadata")
                 assertNoSuchFile("$kapt3StubsPath/bar/UseBKt.java")
+                assertNoSuchFile("$kapt3StubsPath/bar/UseBKt.kaptMetadata")
             }
         }