* extend light client protocol for Electra
Add missing Electra support for light client protocol:
- https://github.com/ethereum/consensus-specs/pull/3811
Tested against PR consensus-spec-tests, the test runner automatically
picks up the new tests once available.
* workaround `version-2-0`: `Error: cannot instantiate: 'SomeUnsignedInt'`
* fix initialization when Electra not scheduled
* try reduce stack size in test
* put correct sync committee branch version into DB
* adjust fork schedule in light client data tests
* further reduce stack size
* split function into multiple parts
* rename variable
* regenerate test reports to cover new Electra tests
* add Nim bug reference
`sizeof` also includes padding between fields, while SSZ defines
`fixedPortionSize` (on type) or `sszSize` (on value) to denote
required bytes to encode. Switch forked block/state readers to SSZ size.
As blocks/states are much larger than the padding, this doesn't affect
practical use cases but is slightly more correct this way.
Extend slot start message and default status bar with information about
current head fork and the next fork transition (corresponding to head).
This is useful to know whether a synced client is aware of a future fork
and can also be useful when syncing from old forks to follow progress
across the various forks.
```
peers: 8 ❯ finalized: 741c2ce2:230474 ❯ head: b330f58b:230477:20 ❯ fork: Capella (next: Deneb:231680) ❯ time: 230599:24 (7379192) ❯ sync: 00h24m (99.63%) 2.6492slots/s (QwQUwQPQDQ:7375263)/opt
```
```
INF 2024-01-12 12:18:00.001+01:00 Slot start topics="beacnde" slot=7379190 epoch=230599 fork="Capella (next: Deneb:231680)" sync="--h--m (99.62%) 0.0000slots/s (wwwwwwwwww:7375167)/opt" peers=0 head=741c2ce2:7375168 finalized=230472:723abe7e delay=1ms861us
```
As followup from #5654, ensure that we still keep the comment around
referring to the correct `forkchoiceUpdated` to use being driven by
the fork schedule.
* use `PayloadAttributesV3` in `nimbus_light_client` for Deneb
From Deneb onward, `forkchoiceUpdated` requires `PayloadAttributesV3`.
In `nimbus_light_client` we still used `PayloadAttributesV2`.
Also clean up two other locations that were already correctly using
`PayloadAttributesV3`, to reduce code duplication.
* fix letter case
Replace sections that need to be maintained with every `ConsensusFork`
related to LC data collection with a generic logic that keeps working
when unrelated parts of Ethereum change.
The templates for `BeaconBlock`, `BeaconBlockBody` and `BeaconState`
are the only ones using a `macro` mechanism for code generation.
This prevents using the dot-syntax style `consensusFork.BeaconFoo`
in some situations, and also tends to trigger naming conflicts,
requiring the `Type` suffix. Furthermore, the `macro` only works
for types that are re-defined in every single `ConsensusFork`.
Replacing with the simpler but more verbose approach used for other
types for consistency and to avoid the downsides of the `macro`.
Furthermore, simplify `test_fixture_sanity_blocks` to use `forks` sugar.