[clang] [clang-format] Separate License text and include blocks (PR #77918)

[via cfe-commits]

seranu wrote:

I am going to rework the change as per the review comments.  I created another PR to add the missing SeparateDefinitionBlocks config parse tests at https://github.com/llvm/llvm-project/pull/78256.
For the rework, shall I create a new PR or can I still use this one?

https://github.com/llvm/llvm-project/pull/77918