When running the import, currently blocks are loaded in batches into a
`seq` then passed to the importer as such.
In reality, blocks are still processed one by one, so the batching does
not offer any performance advantage. It does however require that the
client wastes memory, up to several GB, on the block sequence while
they're waiting to be processed.
This PR introduces a persister that accepts these potentially large
blocks one by one and at the same time removes a number of redundant /
unnecessary copies, assignments and resets that were slowing down the
import process in general.
* partial commit
* fixes
* remove converters too
* revert changes on nimbus_verified_proxy
* revert changes in converter
* revert changes(re-xport) in rpc_types
* update copyright year
* replace types in other binaries
* chain config bug
* fix rebase conflict imcomplete buffer
* fix more rebase buffers
* remove ditto types and converters
* fix the tests
* update copyright year
This is a minimal set of changes to make things work with the new types
in nim-eth - this is the minimal PR that merely resolves
incompatibilities while the full change set would include more cleanup
and migration.
* remove some redundant EH
* avoid pessimising move (introduces a copy in this case!)
* shift less data around when reading era files (reduces stack usage)
