[kotlinp] Split :tools:kotlinp into "common" and "jvm" subprojects

The "common" subproject keeps only backend-neutral logic and depends
only on :kotlinx-metadata library. It takes the name of the former
project - :tools:kotlinp

The "jvm" subproject depends on the "common" one and also depends
on :kotlinx-metadata-jvm. It gets the new name - :tools:kotlinp-jvm

There is a lot of touched files in this commit. The majority of them
is just moved files (tests, test data, etc).

Only the following files were actually modified:
  .space/CODEOWNERS
  build.gradle.kts
  libraries/tools/abi-comparator/build.gradle.kts
  libraries/tools/kotlinp/build.gradle.kts
  libraries/tools/kotlinp/jvm/build.gradle.kts
  plugins/kapt3/kapt3-compiler/build.gradle.kts
  settings.gradle

 ^KT-62340

libraries/tools/kotlinp/jvm/testData/NestedClasses.kt

@@ -0,0 +1,16 @@
+interface A {
+    interface B {
+        interface C
+    }
+
+    companion object D {
+        enum class E {
+            E1,
+            E2,
+        }
+
+        sealed class F {
+            class G : F()
+        }
+    }
+}