[lldb] [DynamicRegisterInfo] Support setting from vector<Register>

Add an overload of DynamicRegisterInfo::SetRegisterInfo() that accepts
a std::vector<Register> as an argument.  This moves the conversion
from DRI::Register to RegisterInfo directly into DynamicRegisterInfo,
and avoids the necessity of creating fully-compatible intermediate
RegisterInfo instances.

While the new method could technically reuse AddRegister(), the ultimate
goal is to replace AddRegister() with SetRegisterInfo() entirely.

Differential Revision: https://reviews.llvm.org/D111435