Fix typos

Summary:
Backport of core PR12543
https://github.com/bitcoin/bitcoin/pull/12543/files

This backport misses the wallet_dump.py part as I'm not sure we want
the dependency in. If this happen the spellcheck linter will catch the
error, so we're safe.

Test Plan:

arc lint --everything

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D3519