Checkstyle naming conventions were changed to allow most of what's in
wpimath. Naming rules were disabled completely in wpimath since almost
all suppressions are for math notation.
Also update Checkstyle to 8.38.
Google changed their style guide from the last time we imported it. This PR brings in those naming changes. The change they made is allowing single letter member, parameter, and local variable names. They also added a lambda naming scheme and I thought it would be good to bring that in too.
