Awscliv2

Fixed
- Typing issue in `py38-` (reported by JonasDev1)

Fixed
- Command print error on `py37`

Added
- Auto-generated documentation
- `--encoding` CLI argument to use an encoding other than `utf-8`

Removed
- Python 3.6 support, now requires Python 3.7 at least

Fixed
- Use `utf-8` encoding by default
- Safe cleanup of temporary files and folders
- Error on an attempt to read from a finished process
- Paths were printed incorrectly on Windows

CI fixes

Fixed

- MacOS `--install` command sometimes tried to remove everything from `$HOME`

Added

- `awsv2 --install` command to install `AWS CLI v2` (Linux and MacOS are supported)
- `awsv2` checks `~/.awscliv2/dist/aws` and `~/aws-cli/aws` paths before fallback to Docker image

Changed

- `awsv2 --update` is now an alias for `awsv2 --install`
- `awsv2 --version` outputs path to current `AWS CLI v2` executable

Fixed

- Subprocesses always wait for all output to be processed
- `awsv2 --assume-role` did not use JSON output correctly