* update go version to 1.18 for api and sdk, go mod tidy
* removes ioutil usage everywhere which was deprecated in go1.16 in favour of io and os packages. Also introduces a lint rule which forbids use of ioutil going forward.
Co-authored-by: R.B. Boyer <4903+rboyer@users.noreply.github.com>
And into token.Store. This change isolates any awareness of token
persistence in a single place.
It is a small step in allowing Agent.New to accept its dependencies.
