Add support to specify metainfo or path of metainfo for linux

[prateekmedia]

Linux systems use metainfo xml file to gather the previous versions of app, description, app home page, etc details which are used for App Stores to display relevant information. Currently we have not way to specify this xml file from deb/rpm/appimage make_configs. It would be good if a parameter is added to specify this file and to specify this file as yaml as well cause xml is not used by flutter_distributor primarily.

Reference: https://freedesktop.org/software/appstream/docs/chap-Quickstart.html Location to package: /usr/share/metainfo/%{id}.metainfo.xml

Metainfo file is also important aspect for flatpak packaging #50