[Sema] Split out -Wformat-type-confusion from -Wformat-pedantic

The warnings now in -Wformat-type-confusion don't align with how we interpret
'pedantic' in clang, and don't belong in -pedantic.

Differential revision: https://reviews.llvm.org/D67775

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@373774 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed