Update Management Console installation from tarball to DEB/RMP package

Starting with Resilio Connect 3.8.0, Management Console DEB, RPM packages are available for Linux OS.

Requirements:
- arch: x64 (amd64, x86_64)
- init manager: systemd (with systemctl)

Note: even though legacy init.d script is available in the packages, it is not guaranteed to work on every GNU/Linux distribution, so it's recommended to use distribution with systemd.

Prior to v3.8.0 Management Console on Linux OS is installed from "resilio-connect-server-linux-x64.tar.gz" tarball which is unpacked to /opt folder by default.

Follow the steps below to update such installation to that via DEB/RPM package:

1. Upgrade the MC to the latest version and stop it.
2. Install the same version of MC using DEB/RPM package. During the installation new service file /lib/systemd/system/resilio-connect-management-console.service  and new Management Console storage folder in /var/opt/resilio-connect-management-console are created.
3. Edit /lib/systemd/system/resilio-connect-management-console.service file and change "user" and "group" to the user that used to run the current MC.
4. Copy the content of the tarball-installed MC's storage folder  /opt/resilio-connect-server/var/ to new storage folder of the package-installed MC /var/opt/resilio-connect-management-console/
5. Start package-installed MC.
6. Disable the MC daemon if it was registered before.