Do not serialize SOURCE-retained annotations

Also, fix the value of "hasAnnotations" flag to reflect if there are any
_non-source_ annotations on a declaration.

Unfortunately, after this change
IncrementalJsCompilerRunnerTestGenerated$PureKotlin.testAnnotations
starts to fail because of the following problem. The problem is that
annotations on property accessors are not serialized yet on JS (see
KT-14529), yet property proto message has setterFlags field which has
the hasAnnotations flag. Upon the full rebuild of the code in that test,
we correctly write hasAnnotations = true, but annotations themselves are
not serialized. After an incremental build, we deserialize property
setter descriptor, observe its Annotations object which happens to be an
instance of NonEmptyDeserializedAnnotationsWithPossibleTargets. Now,
because annotations itself are not serialized, that Annotations object
has no annotations, yet its isEmpty always returns false (see the code).
Everything worked correctly before the change because in
DescriptorSerializer.hasAnnotations, we used Annotations.isEmpty and the
result was the same in the full rebuild and in the incremental scenario.
But now we're actually loading annotations, to determine their
retention, and that's why the setterFlags are becoming different here
and the test fails

 #KT-23360 Fixed

core/descriptors/src/org/jetbrains/kotlin/descriptors/annotations/Annotations.kt

@@ -23,7 +23,13 @@ interface Annotated {
 }
 
 interface Annotations : Iterable<AnnotationDescriptor> {
-
+    /**
+     * @return `true` iff there are no "direct" annotations applicable to this declaration. Note that even if [isEmpty] is `true`,
+     * there may be use-site-targeted annotations applicable to the declaration!
+     *
+     * @see getUseSiteTargetedAnnotations
+     * @see getAllAnnotations
+     */
     fun isEmpty(): Boolean
 
     fun findAnnotation(fqName: FqName): AnnotationDescriptor? = firstOrNull { it.fqName == fqName }
@@ -32,7 +38,9 @@ interface Annotations : Iterable<AnnotationDescriptor> {
 
     fun getUseSiteTargetedAnnotations(): List<AnnotationWithTarget>
 
-    // Returns both targeted and annotations without target. Annotation order is preserved.
+    /**
+     * @return both targeted and annotations without target. Annotation order is preserved.
+     */
     fun getAllAnnotations(): List<AnnotationWithTarget>
 
     companion object {

core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorUtils.kt

@@ -218,6 +218,18 @@ fun Annotated.getAnnotationRetention(): KotlinRetention? {
     return KotlinRetention.valueOf(retentionArgumentValue.enumEntryName.asString())
 }
 
+val Annotated.nonSourceAnnotations: List<AnnotationDescriptor>
+    get() = annotations.filterOutSourceAnnotations()
+
+fun Iterable<AnnotationDescriptor>.filterOutSourceAnnotations(): List<AnnotationDescriptor> =
+    filterNot(AnnotationDescriptor::isSourceAnnotation)
+
+val AnnotationDescriptor.isSourceAnnotation: Boolean
+    get() {
+        val classDescriptor = annotationClass
+        return classDescriptor == null || classDescriptor.getAnnotationRetention() == KotlinRetention.SOURCE
+    }
+
 val DeclarationDescriptor.parentsWithSelf: Sequence<DeclarationDescriptor>
     get() = generateSequence(this, { it.containingDeclaration })