This commit changes the behavior of BitCurve.Add to be more inline
with btcd. It fixes two different bugs:

1) When adding a point at infinity to another point, the other point
   should be returned. While this is undefined behavior, it is better
   to be more inline with the go standard library.
   Thus (0,0) + (a, b) = (a,b)

2) Adding the same point to itself produced the point at infinity.
   This is incorrect, now doubleJacobian is used to correctly calculate it.
   Thus (a,b) + (a,b) == 2* (a,b) and not (0,0) anymore.

The change also adds a differential fuzzer for Add, testing it against btcd.

Co-authored-by: Felix Lange <fjl@twurst.com>

Add more cross-fuzzers to fuzz bls with gnark versus geth's own bls12-381 library

* les: move client pool to les/vflux/server

* les/vflux/server: un-expose NodeBalance, remove unused fn, fix bugs

* tests/fuzzers/vflux: add ClientPool fuzzer

* les/vflux/server: fixed balance tests

* les: rebase fix

* les/vflux/server: fixed more bugs

* les/vflux/server: unexported NodeStateMachine fields and flags

* les/vflux/server: unexport all internal components and functions

* les/vflux/server: fixed priorityPool test

* les/vflux/server: polish balance

* les/vflux/server: fixed mutex locking error

* les/vflux/server: priorityPool bug fixed

* common/prque: make Prque wrap-around priority handling optional

* les/vflux/server: rename funcs, small optimizations

* les/vflux/server: fixed timeUntil

* les/vflux/server: separated balance.posValue and negValue

* les/vflux/server: polish setup

* les/vflux/server: enforce capacity curve monotonicity

* les/vflux/server: simplified requestCapacity

* les/vflux/server: requestCapacity with target range, no iterations in SetCapacity

* les/vflux/server: minor changes

* les/vflux/server: moved default factors to balanceTracker

* les/vflux/server: set inactiveFlag in priorityPool

* les/vflux/server: moved related metrics to vfs package

* les/vflux/client: make priorityPool temp state logic cleaner

* les/vflux/server: changed log.Crit to log.Error

* add vflux fuzzer to oss-fuzz

Co-authored-by: rjl493456442 <garyrong0905@gmail.com>

* les: refactored server handler

* tests/fuzzers/les: add fuzzer for les server handler

* tests, les: update les fuzzer

tests: update les fuzzer

tests/fuzzer/les: release resources

tests/fuzzer/les: pre-initialize all resources

* les: refactored server handler and fuzzer

Co-authored-by: rjl493456442 <garyrong0905@gmail.com>

* tests/fuzzers/abi: better test generation

* tests/fuzzers/abi: fixed packing issue

* oss-fuzz: enable abi fuzzer

* common,crypto: move fuzzers out of core

* fuzzers: move vm fuzzer out from core

* fuzzing: rework cover package logic

* fuzzers: lint

This PR adds re-written difficulty calculators, which are based on uint256. It also adds a fuzzer + oss-fuzz integration for the new fuzzer. It does differential fuzzing between the new and old calculators.

Note: this PR does not actually enable the new calculators.

* added bls fuzzer

* crypto/bls12381: revert bls-changes, fixup fuzzer tests

* fuzzers: split bls fuzzing into 8 different units

* fuzzers/bls: remove (now stale) corpus

* crypto/bls12381: added blsfuzz corpus

* fuzzers/bls12381: fix the bls corpus

* fuzzers: fix oss-fuzz script

* tests/fuzzers: fixups on bls corpus

* test/fuzzers: remove leftover corpus

Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>