[AuRa] Implement blockGasLimitContract

[yperbasis]

We don't currently implement AuRa's custom blockGasLimitContract, but Chiado and other Gnosis test networks use it (search for BlockGasLimitContractTransitions). Because of this the following issue occurred on gnosis_withdrawals_devnet_2 (PR #7150):

[DBUG] [03-21|09:24:12.652] [downloader] Verification failed for header hash=0xc693c0481d4c890d7a4d252171f23e035704b44d2169a176b2ca34c95664707d height=1 err="invalid gas limit: have 12500000, want 10000000 +-= 9764"

[github-actions]

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