Add REGO debugger to Mindev.

This change adds the possibility to start evaluate a REGO-based rule
type in a debugger.

The debugger allows setting breakpoints, stepping, printing source,
and a few other simple utilities.

The debugger is currently very, very, VERY rough around the edges and
could use some love, especially in the reception of events from the
debuggee, which is done inline and not asynchronously.

cmd/dev/app/rule_type/rttst.go

@@ -67,6 +67,7 @@ func CmdTest() *cobra.Command {
 	testCmd.Flags().StringP("token", "t", "", "token to authenticate to the provider."+
 		"Can also be set via the TEST_AUTH_TOKEN environment variable.")
 	testCmd.Flags().StringArrayP("data-source", "d", []string{}, "YAML file containing the data source to test the rule with")
+	testCmd.Flags().BoolP("debug", "", false, "Start REGO debugger (only works for REGO-based rules types)")
 
 	if err := testCmd.MarkFlagRequired("rule-type"); err != nil {
 		fmt.Fprintf(os.Stderr, "Error marking flag as required: %s\n", err)
@@ -98,6 +99,7 @@ func testCmdRun(cmd *cobra.Command, _ []string) error {
 	token := viper.GetString("test.auth.token")
 	providerclass := cmd.Flag("provider")
 	providerconfig := cmd.Flag("provider-config")
+	debug := cmd.Flag("debug").Value.String() == "true"
 
 	dataSourceFileStrings, err := cmd.Flags().GetStringArray("data-source")
 	if err != nil {
@@ -197,7 +199,10 @@ func testCmdRun(cmd *cobra.Command, _ []string) error {
 
 	// TODO: use cobra context here
 	ctx := context.Background()
-	eng, err := rtengine.NewRuleTypeEngine(ctx, ruletype, prov, nil /*experiments*/, options.WithDataSources(dsRegistry))
+	eng, err := rtengine.NewRuleTypeEngine(ctx, ruletype, prov, nil, /*experiments*/
+		options.WithDataSources(dsRegistry),
+		options.WithDebugger(debug),
+	)
 	if err != nil {
 		return fmt.Errorf("cannot create rule type engine: %w", err)
 	}