Global reformatting
As follow up from !1261 (merged), this MR updates the formatting of C++ files using clang-format-11.
I also changed the Python formatter from YAPF to the combination of Black+isort.
As follow up from !1261 (merged), this MR updates the formatting of C++ files using clang-format-11.
I also changed the Python formatter from YAPF to the combination of Black+isort.