Fix EthStats integration with updating blocks

[jframe]

PR description

Fix EthStats not updating blocks. This due the BlockResult containing an Optional.

This is the exception we are currently getting

ERROR | EthStatsService | Failed to send BLOCK ethstats request with error Java 8 optional type `java.util.Optional<org.hyperledger.besu.ethereum.api.jsonrpc.internal.results.BlockAccessListResult>` not supported by default: add Module "com.fasterxml.jackson.datatype:jackson-datatype-jdk8" to enable handling (through reference chain: org.hyperledger.besu.ethstats.request.EthStatsRequest["emit"]->java.util.ArrayList[1]->org.hyperledger.besu.ethstats.report.ImmutableBlockReport["block"]->org.hyperledger.besu.ethereum.api.jsonrpc.internal.results.BlockResult["blockAccessList"])

Fixed Issue(s)

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• Checked out our contribution guidelines?
• Considered documentation and added the doc-change-required label to this PR if updates are required.
• Considered the changelog and included an update if required.
• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

Locally, you can run these tests to catch failures early:

• spotless: ./gradlew spotlessApply
• unit tests: ./gradlew build
• acceptance tests: ./gradlew acceptanceTest
• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests
• hive tests: Engine or other RPCs modified?