KT-65404 KAPT should print a warning if stub generation is triggered for an interface with method bodies but without -Xjvm-default=all or -Xjvm-default=all-compatibility

Merge-request: KT-MR-14139
Merged-by: Pavel Mikhailovskii <Pavel.Mikhailovskii@jetbrains.com>

plugins/kapt3/kapt3-cli/testData/integration-kapt4/defaultMethodsAllNoWarning/Test.kt

@@ -0,0 +1,11 @@
+package test
+
+interface I1 {
+    fun foo() {}
+}
+
+interface I2 {
+    fun bar() {}
+}
+
+class C: I1, I2

plugins/kapt3/kapt3-cli/testData/integration-kapt4/defaultMethodsAllNoWarning/build.txt

@@ -0,0 +1,18 @@
+# mkdir
+output/stubs
+
+# kapt
+-Xjvm-default=all
+-language-version 2.0
+-Xuse-kapt4
+-Kapt-mode=stubs
+-Kapt-stubs=output/stubs
+-Kapt-classes=output/classes
+-Kapt-sources=output/sources
+-Kapt-classpath=output/ap
+-d output/classes
+-cp %KOTLIN_STDLIB%
+Test.kt
+
+# output
+warning: k2 kapt is an experimental feature. Use with caution.