The existing code added the git commit info (`GIT_COMMIT_HASH` and `GIT_BRANCH`) to every file, which was a problem for leveraging `ccache` to cache build objects. This change adds a separate C++ file from where these compile-time variables are propagated to wherever they are needed. A new CMake file is added to set the commit info if the `git` binary is available.
Per XLS-0095, we are taking steps to rename ripple(d) to xrpl(d).
This change specifically removes all copyright notices referencing Ripple, XRPLF, and certain affiliated contributors upon mutual agreement, so the notice in the LICENSE.md file applies throughout. Copyright notices referencing external contributions remain as-is. Duplicate verbiage is also removed.
