Bitrate or resolution selection in the add-on

*I'm submitting a ...*
- [ ] bug report
- [x] feature request
- [ ] support request

## General information
I would like to be able to select the max. resolution or max. bitrate from within the Netflix add-on, and not from within the **inputstream.adaptive** settings.

### Prerequisites

* [x] Are you running the latest version?

### Description

My situation is a common situation. I run LibreELEC from a Raspberry Pi 3B+ and this device can play 1080p fine in one add-on (VTM GO). So I do want 1080p for those add-ons using **inputstream.adaptive** that do work fine, but Netflix is not one of them. So only for Netflix I would like to limit playback to 720p (or an equivalent bitrate).

~It should not be hard to have a feature like this as the bitrate can be added to the **inputstream.adaptive** ListItem as property **inputstream.adaptive.max_bandwidth**.~
This does not seem to be an option, probably should be part of writing the MPD manifest.

## Context (Environment)
LibreELEC 9.0.2 on Raspberry Pi 3B+

### Installation
* [x] I installed the plugin via zip from the Releases page
* [ ] I´m using the Netflix Repo
* [ ] I´m using a different source (Please tell which)

### Operating System
* [ ] Linux (x86/x64)
* [ ] OSX (x86/x64)
* [ ] Windows (x86/x64)
* [x] Linux (ARM)
* [ ] Android

Start by reviewing the Netflix add-on's inputstream.adaptive integration and the MPD manifest-writing path mentioned in the issue. Determine how a per-add-on maximum resolution or bitrate could be represented, then verify the selected limit during playback on LibreELEC 9.0.2 with a Raspberry Pi 3B+.

Written by the indexing model from the issue text.