[BOLT] Track fragment info for all split fragments

[BOLT] Track fragment info for all split fragments

To generate all symbols correctly, it is necessary to record the address
of each fragment. This patch moves the address info for the main and
cold fragments from BinaryFunction to FunctionFragment, where this data
is recorded for all fragments.

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D132051