[android] add sign task

haxetool/core.js

@@ -46,6 +46,7 @@ class Config {
             mobileHeight: null,
             fps: 60,
         };
+        this.key = null;
         if (params) {
             this.update(params);
             this.afterUpdate();
@@ -68,6 +69,7 @@ class Config {
         if (params.macros !== undefined) this.macros = this.macros.concat(params.macros);
         if (params.flags !== undefined) this.flags = this.flags.concat(params.flags);
         if (params.meta !== undefined) this.meta = {...this.meta, ...params.meta};
+        if (params.key !== undefined) this.key = params.key;
         if (this.meta.icon) this.icon = Config.absolutePath(this.meta.icon);
     }