[linter] Move the clang format config file to the root so it applies to chronik cpp as well

Summary: There is no way to tell clang-format to use a specific config file before version 14, so it needs to be in a parent directory to apply to chronik.

Test Plan:

arc lint --everything

Reviewers: #bitcoin_abc, tobias_ruck

Reviewed By: #bitcoin_abc, tobias_ruck

Differential Revision: https://reviews.bitcoinabc.org/D11908