[AArch64] Move branch relaxation after bbsection assignment

[AArch64] Move branch relaxation after bbsection assignment

Because branch relaxation needs to factor in if branches target
a block in the same section or a different one, it needs to run
after the Basic Block Sections / Machine Function Splitting passes.

Because Jump table compression relies on block offsets remaining
fixed after the table is compressed, we must also move the JT
compression pass.

The only tests affected are ones enforcing just the ordering and
the a few that have basic block ids changed because RenumberBlocks
hasn't run yet.

Differential Revision: https://reviews.llvm.org/D153829