wire scalafix initialization logs to proper logger

[bjaglin]

Follows https://github.com/scalacenter/scalafix/pull/1565/files#r825365856

 sbt> scalafix dependency:SemanticRule@ch.epfl.scala::example-scalafix-rule:1.4.0
-Loading external rule(s) built against an old version of scalafix (0.9.16).
-This might not be a problem, but if you run into unexpected behavior, you should either:
-1. downgrade scalafix to 0.9.16
-2. try a more recent version of the rules(s) if available; request the rule maintainer
-   to build against scalafix 0.10.0 or later if that does not help
+[info] Loading external rule(s) built against an old version of scalafix (0.9.16).
+[info] This might not be a problem, but if you run into unexpected behavior, you should either:
+[info] 1. downgrade scalafix to 0.9.16
+[info] 2. try a more recent version of the rules(s) if available; request the rule maintainer
+[info]    to build against scalafix 0.10.0 or later if that does not help
 ...