Make strencodings functions use string_view
Summary:
Make ParseHex use string_view
https://github.com/bitcoin/bitcoin/pull/25001/commits/c1d165a8c2678c31aced5e1d46231d9996b0774a
Make IsHex use string_view
https://github.com/bitcoin/bitcoin/pull/25001/commits/40062997f223d88d4f92aaae4622a31476686163
Make IsHexNumber use string_view
https://github.com/bitcoin/bitcoin/pull/25001/commits/963bc9b576f0a62caffede2ce32830aef3473995
Make SanitizeString use string_view
https://github.com/bitcoin/bitcoin/pull/25001/commits/d648b5120b2fefa9e599898bd26f05ecf4428fac
This is a partial backport of core#25001
Depends on D17147
Test Plan: ninja all check-all bitcoin-fuzzers
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Subscribers: Fabien
Differential Revision: https://reviews.bitcoinabc.org/D17148