[FIR] Fix IrInlineBodiesHandler

Validate that inline function actually is present in at least on of the
modules, not in all of them. That enables support of MODULE directive
in boxInline tests for FIR.

Also, hide a few minor style fixes in this commit

compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/session/FirSessionFactory.kt

@@ -197,6 +197,7 @@ object FirSessionFactory : FirAbstractSessionFactory() {
         }
     }
 
+    @OptIn(SessionConfiguration::class)
     @TestOnly
     fun createEmptySession(): FirSession {
         return object : FirSession(null, Kind.Source) {}.apply {