[clang] [clang][analyzer] Add plist macro formatting (PR #156046)

[Balazs Benics via cfe-commits]

steakhal wrote:

Speaking of testing, we should probably not overdo it. Clang format is a different component. They likely want to remain flexible. If we pin their output too hard, they would become unhappy long term.
Consequently, having a couple is desired, but other than that if we want to pin something then it should be that formatting resulted in some non empty but different result than the input.

Speaking of the plist test, I frankly hate them. If we can get away with just unittest, I'd prefer those instead.
Raw plists are too bad to read.

https://github.com/llvm/llvm-project/pull/156046