JVM_IR: reuse MethodNodes for inline functions in same module

This fixes the weird cases when a class gets overwritten by an imperfect
copy, reduces the number of classes in the output if an inline function
contains an inline call that causes it to have regenerated anonymous
objects, and makes inlining of same module functions a bit faster in
general. On the other hand, this may increase memory footprint a bit
because classes cannot be flushed to the output jar, as the inliner
would not be able to locate classes for anonymous objects if they have
already been unloaded from memory.

jps-plugin/testData/incremental/withJava/other/innerClassNotGeneratedWhenRebuilding/directives.txt

@@ -1 +0,0 @@
-// IGNORE_BACKEND: JVM_IR