log: allow external definition of log handling (#1561)

* poc

* linter: fix

---------

Co-authored-by: Ryan O'Hara-Reid <ryan.oharareid@thrasher.io>

log/custom_log_hooks_test.go

@@ -0,0 +1,11 @@
+package log
+
+import "testing"
+
+func TestSetCustomLoghook(t *testing.T) {
+	t.Parallel()
+	logHook := func(_ string, _ string, _ ...interface{}) (bypassLibraryLogSystem bool) {
+		return false
+	}
+	SetCustomLogHook(logHook)
+}