Ensure not only Packet is valid, but also it's Parents are valid

This bug was found by fuzzer, that used *View::FromBytes(...) method on
packet to create instance of WriteCurrentIacLapView which content was
longer than what it's parent packet,  Command can contain.

Generated IsValid() method on WriteCurrentIacLapView was not calling
parent packet IsValid() method to check if size is proper.

IsValid() method in Builders doesn't have that issue, therefore when
View was converted to Builder, crash on assert occured.

This patch adds the missing call to parent IsValid() method.

This never occured in production code, because we always construct
partents, check theri validity, and then construct child views.

Test: run bluetooth_gd_fuzz_test
Bug: 177047996
Change-Id: Ife65b865acd745d67048c6d571ad555216098935