[AMDGPU][Libomptarget] Move Kernel/Symbol info tables to RTLDeviceInfoTy

Two globals KernelInfoTable & SymbolInfoTable are moved
into RTLDeviceInfoTy class.
This builds on the top of D102691.
[2/2]

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D102692