[clang] [llvm] Reland "[Utils] Add new --update-tests flag to llvm-lit" (PR #153821)

[Henrik G. Olsson via llvm-commits]

hnrklssn wrote:

Deferred the diff test update changes to https://github.com/llvm/llvm-project/pull/154147

https://github.com/llvm/llvm-project/pull/153821