refactor: is_some utils for Header

[tcoratger]

Describe the change

At the moment, there are different places of the codebase where we use the is_some method for some fields of the header structure like:

reth/crates/primitives/src/header.rs

Line 260 in 27caf7b

self.parent_beacon_block_root.is_some()

or

reth/crates/consensus/common/src/validation.rs

Line 53 in 27caf7b

} else if header.excess_blob_gas.is_some() {

For ease of use and a slightly less verbose implementation, wouldn't it be useful to implement directly within the Header structure methods such as is_some_excess_blob_gas, is_some_parent_beacon_block_root, etc?

Additional context

No response