Finish [[https://github.com/bitcoin/bitcoin/pull/14796 | PR14796]] by removing and/or renaming old functions in
`rpc/util`.
Renaming done with `sed "s/ToStringWithArgs/ToString/g" <files>`
Depends on D5710, D5712, D5713, D5714. D5716, D5717, D5720, D5722, D5725