[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

compiler/testData/diagnostics/foreignAnnotationsTests/tests/externalAnnotations/fieldNotNull.kt

@@ -0,0 +1,39 @@
+// FIR_IDENTICAL
+// FILE: ClassWithExternalAnnotatedMembers.java
+import org.jetbrains.annotations.NotNull;
+
+public class ClassWithExternalAnnotatedMembers {
+    public String externalNotNullField;
+
+    @NotNull
+    public String explicitNotNullField;
+
+    public static String staticExternalNotNullField;
+
+    @NotNull
+    public static String staticExplicitNotNullField;
+}
+
+// FILE: usage.kt
+fun test() {
+    val x = ClassWithExternalAnnotatedMembers()
+    x.externalNotNullField<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+    x.explicitNotNullField<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+
+    ClassWithExternalAnnotatedMembers.staticExternalNotNullField<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+    ClassWithExternalAnnotatedMembers.staticExplicitNotNullField<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+}
+
+fun String.foo() {
+
+}
+
+// FILE: annotations.xml
+<root>
+    <item name='ClassWithExternalAnnotatedMembers externalNotNullField'>
+        <annotation name='org.jetbrains.annotations.NotNull'/>
+    </item>
+    <item name='ClassWithExternalAnnotatedMembers staticExternalNotNullField'>
+        <annotation name='org.jetbrains.annotations.NotNull'/>
+    </item>
+</root>