Build and install a magma package in AGW

Description: Purpose of this document is describe how to build and install a magma package in AGW.

Environment: AGW

Steps:

Clone or Update your local repository. In any machine (i.e. your computer) clone the magma repo and checkout the version from where you would like to build your package. For example, for v1.8 you can run:
```
git clone https://github.com/magma/magma.git
git checkout v1.8
```
Install prerequisites. Make sure you have installed all the tools specified in the prerequisites https://magma.github.io/magma/docs/basics/prerequisites#prerequisites
Build and create deb package. To build an AGW package, use the script located at $MAGMA_ROOT/lte/gateway/fabfile.py. The commands below will create a vagrant machine, then build and create a deb package.

The following commands are to be run from $MAGMA_ROOT/lte/gateway on your host machine. To create a package for production, run
```
fab release package
```
To create a package for development or testing, run
```
fab dev package
```
The dev flag will compile all C++ services with Debug compiler flags and enable ASAN. This is recommended for testing only as it will impact performance. In contrast, the production package has C++ services built with RelWithDebInfo compiler flags.
Locate the packages. Once the above command finished. You need to enter the VM to verify the deb packages are there.
```
vagrant ssh magma
cd ~/magma-packages/
```
You will need only the ones that say magma_1.1.XXX and magma-sctpd_1.1.XXX (for v1.1 versions)
Download the package. You can download the files to your computer from the vagrant machine. To do so, you can install a vagrant plugin in your computer and then download the package from the VM to your computer with the following commands:
```
vagrant plugin install vagrant-scp
vagrant scp magma: ~/magma-packages/<deb_package>
```
Upload the package to AGW that you would like to install.
Install the package. In order to install the new deb package in AGW, you can run
```
sudo apt -f install MAGMA_PACKAGE
```

Restart the magma services

sudo service magma@* stop
sudo service magma@magmad restart

You can verify the installed version with
```
apt show magma
```