util: remove undefined handling from bytesToHex

[gabrocheleau]

This PR fixes #3998 by updating bytesToHex so that it throws on undefined instead of returning 0x
Fixes #3958 by deprecating the account constructor and updating the docs.

[codecov]

Codecov Report

Attention: Patch coverage is 92.68293% with 3 lines in your changes missing coverage. Please review.

Project coverage is 79.51%. Comparing base (aba2ffc) to head (281a423).
Report is 1 commits behind head on master.

Additional details and impacted files

Flag	Coverage Δ
block	83.34% <ø> (ø)
blockchain	89.32% <ø> (ø)
client	67.99% <85.71%> (+0.03%)	⬆️
common	97.51% <ø> (ø)
devp2p	86.78% <ø> (ø)
evm	73.03% <ø> (ø)
mpt	89.45% <ø> (+0.05%)	⬆️
statemanager	69.08% <ø> (ø)
static	99.11% <ø> (ø)
tx	90.59% <ø> (ø)
util	89.36% <96.29%> (-0.17%)	⬇️
vm	55.17% <ø> (ø)

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[jochem-brouwer]

I see changes to the account file (which is good!), could you directly deprecate the constructor of Account and document that createAccount should be used? Context: #3958. I think it's fine to also do that in this PR and not create a new one, since it's only docs.

[gabrocheleau]

Done!

[holgerd77]

Nice, LGTM! 🙂 🙏