JVM_IR: collect free type parameters when serializing FIR metadata

The "free" in "createFreeFakeLambdaDescriptor" and such refers to the
fact that there are no references to type parameters from outside the
current declaration. This is necessary because at the point where the
metadata is written, the type parameters may not even be in scope (e.g.
local delegated properties are serialized at class level, but may refer
to function-scope type parameters).

compiler/testData/codegen/box/functions/functionNtoStringGeneric.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not