[Feature] Add manual helper deserde for pending block

[mattsse]

Component

rpc

Describe the feature you would like

ref #2117

for some reasons client remove fields from the rpc response for pending block.

this is very inconvenient because we would need to
a) make those optional
b) use a different type for pending block

instead we can use manual deserde for the pending block and use default values when we deserialize the block

TODO

• add manual helper deserde function for rpc Block and Header rpc types that use default values if those fields are missing

we only want this for the pending block so we need to check this when we send the getBlock request and deserialize accordingly

Additional context

No response