Improve implementation around config (#1122)

* refactor config

* fix saas config

* feat(config): scanmodule for each server in config.toml

* feat(config): enable to specify containersOnly in config.toml

* add new keys of config.toml to discover.go

* fix summary output, logging

config/scanmodule_test.go

@@ -0,0 +1,65 @@
+package config
+
+import (
+	"testing"
+)
+
+func TestScanModule_IsZero(t *testing.T) {
+	tests := []struct {
+		name  string
+		modes []byte
+		want  bool
+	}{
+		{
+			name:  "not zero",
+			modes: []byte{OSPkg},
+			want:  false,
+		},
+		{
+			name:  "zero",
+			modes: []byte{},
+			want:  true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := ScanModule{}
+			for _, b := range tt.modes {
+				s.Set(b)
+			}
+			if got := s.IsZero(); got != tt.want {
+				t.Errorf("ScanModule.IsZero() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestScanModule_validate(t *testing.T) {
+	tests := []struct {
+		name    string
+		modes   []byte
+		wantErr bool
+	}{
+		{
+			name:    "valid",
+			modes:   []byte{},
+			wantErr: false,
+		},
+		{
+			name:    "err",
+			modes:   []byte{WordPress, Lockfile, Port},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := ScanModule{}
+			for _, b := range tt.modes {
+				s.Set(b)
+			}
+			if err := s.ensure(); (err != nil) != tt.wantErr {
+				t.Errorf("ScanModule.validate() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}