Kapt, Refactoring: Introduce 'KaptOptions'

1. Use 'KaptOptions' for all kapt options, including paths and flags.
2. Use a single 'KAPT_OPTIONS' compiler configuration key for setting all options (using a mutable KaptOptions.Builder).
3. Pass 'KaptOptions' instead of separate flags.
4. Remove 'KaptPaths'.
5. Remove deprecated 'aptOnly' CLI option.

libraries/tools/kotlin-maven-plugin/src/main/java/org/jetbrains/kotlin/maven/kapt/KaptJVMCompilerMojo.java

@@ -94,7 +94,7 @@ public class KaptJVMCompilerMojo extends K2JVMCompileMojo {
     ) {
         List<KaptOption> options = new ArrayList<>();
 
-        options.add(new KaptOption("aptOnly", true));
+        options.add(new KaptOption("aptMode", "stubsAndApt"));
         options.add(new KaptOption("useLightAnalysis", useLightAnalysis));
         options.add(new KaptOption("correctErrorTypes", correctErrorTypes));
         options.add(new KaptOption("mapDiagnosticLocations", mapDiagnosticLocations));