[FIR] add tests on external annotations

Tests are excluded in COMPILED_JAVA mode because in this
mode external annotations are not present at all

^KT-62310

analysis/low-level-api-fir/testData/getOrBuildFir/wholeDeclaration/externalJavaAnnotation.kt

@@ -0,0 +1,19 @@
+// SKIP_WHEN_OUT_OF_CONTENT_ROOT
+// FILE: usage.kt
+<expr>
+fun test() = ClassWithExternalAnnotatedMembers().externalNotNullMethod()
+</expr>
+
+// FILE: ClassWithExternalAnnotatedMembers.java
+public class ClassWithExternalAnnotatedMembers {
+    public String externalNotNullMethod() {
+        return "";
+    }
+}
+
+// FILE: annotations.xml
+<root>
+    <item name='ClassWithExternalAnnotatedMembers java.lang.String externalNotNullMethod()'>
+        <annotation name='org.jetbrains.annotations.NotNull'/>
+    </item>
+</root>

analysis/low-level-api-fir/testData/getOrBuildFir/wholeDeclaration/externalJavaAnnotation.txt

@@ -0,0 +1,14 @@
+KT element: KtNamedFunction
+FIR element: FirSimpleFunctionImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+public final [ResolvedTo(BODY_RESOLVE)] fun test(): R|kotlin/String| {
+    ^test R|/ClassWithExternalAnnotatedMembers.ClassWithExternalAnnotatedMembers|().R|/ClassWithExternalAnnotatedMembers.externalNotNullMethod|()
+}
+
+FIR FILE:
+FILE: [ResolvedTo(IMPORTS)] usage.kt
+    public final [ResolvedTo(BODY_RESOLVE)] fun test(): R|kotlin/String| {
+        ^test R|/ClassWithExternalAnnotatedMembers.ClassWithExternalAnnotatedMembers|().R|/ClassWithExternalAnnotatedMembers.externalNotNullMethod|()
+    }

analysis/low-level-api-fir/testData/getOrBuildFir/wholeDeclaration/notNullJavaAnnotation.kt

@@ -0,0 +1,15 @@
+// SKIP_WHEN_OUT_OF_CONTENT_ROOT
+// FILE: usage.kt
+<expr>
+fun test() = ClassWithExternalAnnotatedMembers().notNullMethod()
+</expr>
+
+// FILE: ClassWithExternalAnnotatedMembers.java
+import org.jetbrains.annotations.NotNull;
+
+public class ClassWithExternalAnnotatedMembers {
+    @NotNull
+    public String notNullMethod() {
+        return "";
+    }
+}

analysis/low-level-api-fir/testData/getOrBuildFir/wholeDeclaration/notNullJavaAnnotation.txt

@@ -0,0 +1,14 @@
+KT element: KtNamedFunction
+FIR element: FirSimpleFunctionImpl
+FIR source kind: KtRealSourceElementKind
+
+FIR element rendered:
+public final [ResolvedTo(BODY_RESOLVE)] fun test(): R|kotlin/String| {
+    ^test R|/ClassWithExternalAnnotatedMembers.ClassWithExternalAnnotatedMembers|().R|/ClassWithExternalAnnotatedMembers.notNullMethod|()
+}
+
+FIR FILE:
+FILE: [ResolvedTo(IMPORTS)] usage.kt
+    public final [ResolvedTo(BODY_RESOLVE)] fun test(): R|kotlin/String| {
+        ^test R|/ClassWithExternalAnnotatedMembers.ClassWithExternalAnnotatedMembers|().R|/ClassWithExternalAnnotatedMembers.notNullMethod|()
+    }