azure-cli package could lose some weight

The `azure-cli` package (Ubuntu Xenial) could stand to lose some weight.

😲 and 😳 don't begin to describe my reaction at the size difference between the AWS CLI and the Azure CLI packages.

```
Package: awscli
Version: 1.11.13-1ubuntu1~16.04.0
Depends: python3, python3-botocore (>= 1.4.70), python3-colorama, python3-docutils, python3-rsa, python3-s3transfer, python3:any (>= 3.3.2-2~)
Installed-Size: 2.9 MB

Package: azure-cli
Version: 2.0.45-1~xenial
Installed-Size: 347 MB
Depends: libc6 (>= 2.17), libssl1.0.0 (>= 1.0.2~beta3)
```

* Why must the package bundle its own version of Python 3.6? Couldn't it just depend on a system `python3` (on platforms where it is known there is a recent enough Python 3)?
* Why does that bundled version also include the Python 3.6 test suite (55.8 MB)?
* Why are all .py files precompiled to .pyc (twice in the case of the stdlib)?
* Why are the py2 versions of all files with `_py3` variants even included if `az` is always run with Python 3?

It's also not just about the size; install speed is also a thing. It takes 50 seconds to install the single `azure-cli` package on Azure machine, with its 39 000 files (`dpkg-query -L azure-cli | wc -l`: 39094), just a little less than installing the twentyish packages that comprise all of `awscli`'s dependencies (that can be used by other software on the system).