[clangd] Minor code style cleanups in Protocol.h. NFC
[clangd] Minor code style cleanups in Protocol.h. NFC

- Remove a parameter name that was misspelled (OS used for non-stream
  parameter)
- Declare operator == (TextEdit, TextEdit) outside the struct, for
  consistency with other user-declared ops in our code.
- Fix naming style of a parameter.

git-svn-id: a34e9779ed74578ad5922b3306b3d80a0c825546@359866 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra