feat(lib): use Checker type instead of ad-hoc logic (#318)

This makes each check into its own type that has encapsulated check
logic, meaning that it's easier to add new checker implementations in
the future.

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/policy/checkresult.go

@@ -0,0 +1,18 @@
+package policy
+
+import (
+	"log/slog"
+
+	"github.com/TecharoHQ/anubis/lib/policy/config"
+)
+
+type CheckResult struct {
+	Name string
+	Rule config.Rule
+}
+
+func (cr CheckResult) LogValue() slog.Value {
+	return slog.GroupValue(
+		slog.String("name", cr.Name),
+		slog.String("rule", string(cr.Rule)))
+}