feat: add discovery port function

[mattsse]

🤖 Generated by Copilot at 3053748

This pull request adds a default socket address for the discv4 discovery module and updates the network configuration to use it. It also improves the API and documentation of the network and discv4 crates.

[codecov]

Codecov Report

Merging #4543 (3053748) into main (2de63c6) will increase coverage by 0.01%.
Report is 1 commits behind head on main.
The diff coverage is 42.85%.

Files Changed	Coverage Δ
crates/net/discv4/src/lib.rs	64.95% <ø> (+0.06%)	⬆️
crates/net/network/src/config.rs	64.63% <42.85%> (-1.90%)	⬇️

... and 5 files with indirect coverage changes

Flag	Coverage Δ
integration-tests	16.68% <42.85%> (-0.02%)	⬇️
unit-tests	63.99% <42.85%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
reth binary	30.83% <ø> (ø)
blockchain tree	83.58% <ø> (ø)
pipeline	90.56% <ø> (ø)
storage (db)	75.32% <ø> (ø)
trie	94.88% <ø> (ø)
txpool	47.99% <ø> (+0.48%)	⬆️
networking	77.39% <42.85%> (-0.07%)	⬇️
rpc	57.37% <ø> (ø)
consensus	63.40% <ø> (ø)
revm	31.67% <ø> (ø)
payload builder	6.34% <ø> (ø)
primitives	86.52% <ø> (+0.01%)	⬆️