Tests update 10.2: Difficulty Tests

The recent tests changes:

Old difficulty tests removed from BasicTests folder
Introduce new difficulty formula test vectors for bomb delay check in DifficultyTests folder

Announcement

The test process diagram: http://tinyurl.com/2ctak8yn
Reminder of a brand new web interface for test debugging: http://retesteth.ethdevops.io/web/
Tests stats on latest builds: http://retesteth.ethdevops.io/
(implement test RPC support or t8ntool protocol to apply for the page. https://ethereum-tests.readthedocs.io/en/latest/t8ntool-ref.html)
Previous release link: https://github.com/ethereum/tests/releases/tag/v10.1

Test format

New test folder for new test suite DifficultyTestsFiller in /src
and DifficultyTests in root

Tests Fillers

GeneralStateTests Filled

Test Regeneration

Update all:
#984

• Documentation
  PR #981

• invalid EC signature recovery test
  PR #973

• remove outdated difficulty tests
  PR #976
  PR ethereum/legacytests#1

• introduce reworked DifficultyTests
  PR #977

• difficulty tests for ArrowGlacier
  PR #972

• more transaction tests
  PR #979
  PR #969
  PR #982
  PR #984
  PR #988

• Travis validator script for new test formats
  PR #980

Upcoming changes:

Implement malicious rlp tests in StateTest or BlockchainTest format (need more debugging with t8n)
Besu retesteth RPC support (web vmtracing support)
Random state test script