[lldb] Remove GDBRemoteDynamicRegisterInfo (#208067)
At this point, GDBRemoteDynamicRegisterInfo is an idempotent wrapper
around DynamicRegisterInfo. Its remaining methods are unimplemented as
of 3f5fd4b3c1d670649b59f3631287b6f54c6b85ee, so the only functional
difference is that it provides public copy and copy-assign constructors.
I propose that GDBRemoteDynamicRegisterInfo be removed in favor of
DynamicRegisterInfo.
