[Utils][LoongArch](5/6) Add a --bits-endian option to extract-section.py

This is a split patch of D115862 which adds a --bits-endian option to
extract-section to make it possible to print bits in specified endianness.
It means that we can print instruction encoding of some targets like LoongArch
as bits[0] to bits[31] from right to left by specifing --bits-endian little.

Differential revision: https://reviews.llvm.org/D116100