BranchFolder cleanup is required for the new jump table-related feature.
In order for our pass to access the BranchFolding.h header file, it has
been moved to the include/ directory.

A new jump table-related feature is being introduced. Pass and its
related files have been renamed from NanoMipsCompressJumpTables to
NanoMipsOptimizeJumpTablesas a result.

Some jump tables may not have any effect on the address of the following
branch, making them redundant. This optimization pass identifies such
tables and removes any associated code. Pass will then attempt to
compress any remaining jump tables.

The NMOptimizeJumpTables pass has been registered and a relevant
regression test has been added. The test will validate the removal of
redundant jump tables.