Sync gas price

[claravanstaden]

snowbridge companion: Snowfork/snowbridge#1188

[vgeddes]

Since beacon headers are now imported on-demand, we need to adjust the EMA algorithm. Updates which are much more recent, ie thousands of blocks compared to the last recorded value) should dominate the EMA.

The scaling factor should be dynamically adjusted so that it ranges between [0.2, 1]:

Window = EPOCHS_PER_SYNC_COMMITTEE_PERIOD * SLOTS_PER_EPOCH
ScalingFactor = Min(
   0.2,
   (Min(Window, Update.Slot) - LastRecordedSlot) / Window
)
EMA = EMA + ScalingFactor * (Update.GasPrice - EMA)

Let me know what you think. This is just an idea.

[yrong]

Updates which are much more recent should dominate the EMA, ...scaling factor should be dynamically adjusted so that it ranges between [0.2, 1]

Yeah, that make sense.

Btw, is there something wrong with the formula for ScalingFactor? Assume the LastRecordedSlot is 1 and Update.Slot is 8192, the formula should be something as following?

[alistair-singh]

The scaling factor should be dynamically adjusted so that it ranges between [0.2, 1]:

Seems like this code was reverted? Did we find that it did not matter? The new implementation is much simpler.