fss0: Support experimental content

Use key `fss0experimental=1` in a boot entry with `fss0=` defined to enable experimental content.

(Older versions of hekate will just skip any experimental content.)

bootloader/hos/hos_config.c

@@ -213,6 +213,15 @@ static int _config_exo_user_pmu_access(launch_ctxt_t *ctxt, const char *value)
 
 static int _config_fss(launch_ctxt_t *ctxt, const char *value)
 {
+	LIST_FOREACH_ENTRY(ini_kv_t, kv, &ctxt->cfg->kvs, link)
+	{
+		if (!strcmp("fss0experimental", kv->key))
+		{
+			ctxt->fss0_enable_experimental = *kv->val == '1';
+			break;
+		}
+	}
+
 	return parse_fss(ctxt, value, NULL);
 }