Re-add header fields with values used in Ethereum 2.0

[karlb]

Implementation of CIP draft: https://github.com/celo-org/celo-proposals/discussions/370

[github-actions[bot]]

Coverage from tests in ./e2e_test/... for ./consensus/istanbul/... at commit b325dc52112e795aee0bef0a47c68b9cbbad8e1e

coverage: 48.6% of statements across all listed packages

coverage:  60.0% of statements in consensus/istanbul
coverage:  42.2% of statements in consensus/istanbul/announce
coverage:  55.7% of statements in consensus/istanbul/backend
coverage:   0.0% of statements in consensus/istanbul/backend/backendtest
coverage:  24.3% of statements in consensus/istanbul/backend/internal/replica
coverage:  58.6% of statements in consensus/istanbul/core
coverage:  50.0% of statements in consensus/istanbul/db
coverage:   0.0% of statements in consensus/istanbul/proxy
coverage:  64.4% of statements in consensus/istanbul/uptime
coverage:  51.8% of statements in consensus/istanbul/validator
coverage:  79.2% of statements in consensus/istanbul/validator/random

[github-actions[bot]]

[codecov[bot]]

Codecov Report

Patch coverage: 65.08% and project coverage change: +1.00 :tada:

Comparison is base (71bdbcf) 54.30% compared to head (c835406) 55.30%.

:exclamation: Current head c835406 differs from pull request most recent head 19616c8. Consider uploading reports for the commit 19616c8 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2124 +/- ## ========================================== + Coverage 54.30% 55.30% +1.00% ========================================== Files 692 674 -18 Lines 115642 113504 -2138 ========================================== - Hits 62795 62770 -25 + Misses 49014 46918 -2096 + Partials 3833 3816 -17 ``` | [Impacted Files](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org) | Coverage Δ | | |---|---|---| | [cmd/devp2p/internal/ethtest/transaction.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y21kL2RldnAycC9pbnRlcm5hbC9ldGh0ZXN0L3RyYW5zYWN0aW9uLmdv) | `0.00% <0.00%> (ø)` | | | [cmd/geth/chaincmd.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y21kL2dldGgvY2hhaW5jbWQuZ28=) | `0.00% <0.00%> (ø)` | | | [cmd/geth/main.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y21kL2dldGgvbWFpbi5nbw==) | `21.39% <ø> (+0.91%)` | :arrow_up: | | [cmd/geth/usage.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y21kL2dldGgvdXNhZ2UuZ28=) | `10.90% <ø> (ø)` | | | [cmd/utils/flags.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y21kL3V0aWxzL2ZsYWdzLmdv) | `2.56% <0.00%> (ø)` | | | [consensus/istanbul/utils.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y29uc2Vuc3VzL2lzdGFuYnVsL3V0aWxzLmdv) | `47.10% <ø> (+1.13%)` | :arrow_up: | | [contracts/currency/currency.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y29udHJhY3RzL2N1cnJlbmN5L2N1cnJlbmN5Lmdv) | `55.00% <ø> (ø)` | | | [contracts/election/election.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y29udHJhY3RzL2VsZWN0aW9uL2VsZWN0aW9uLmdv) | `25.00% <ø> (ø)` | | | [contracts/epoch\_rewards/epoch\_rewards.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y29udHJhY3RzL2Vwb2NoX3Jld2FyZHMvZXBvY2hfcmV3YXJkcy5nbw==) | `88.88% <ø> (ø)` | | | [contracts/freezer/freezer.go](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org#diff-Y29udHJhY3RzL2ZyZWV6ZXIvZnJlZXplci5nbw==) | `70.00% <ø> (ø)` | | | ... and [48 more](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org) | | ... and [30 files with indirect coverage changes](https://app.codecov.io/gh/celo-org/celo-blockchain/pull/2124/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=celo-org)

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