MediaContainer class is now a list

[Dr-Blank]

Description

fetchItems returns a MediaContainer, exactly how server does and is also a python list! Hence it would not break any current api.
additionally, it now supports totalSize attr

The only breaking change is that MediaContainer can now only accept initpath and parent as keword-only arguments in its initialisation, which I don't think anyone would be using.

Fixes #1372

Type of change

Please delete options that are not relevant.

• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the docstring for new or existing methods
• I have added tests when applicable

[JonnyWong16]

This looks greats. It seems to be mostly working, but is it possible to load the other MediaContainer attributes as well?

>> results = plex.library.section("Movies (Test)").all()  # results is now a MediaContainer
>> results.librarySectionID  # this is None

<MediaContainer size="17" allowSync="1" art="/:/resources/movie-fanart.jpg" identifier="com.plexapp.plugins.library" librarySectionID="41" librarySectionTitle="Movies (Test)" librarySectionUUID="e9535986-3fd3-4f88-9793-77a50b04dd01" mediaTagPrefix="/system/bundle/media/flags/" mediaTagVersion="1708667686" thumb="/:/resources/movie.png" title1="Movies (Test)" title2="All Movies (Test)" viewGroup="movie" viewMode="65592">

results is initialized with empty data = Element('MediaContainer') which never gets updated with the attributes from the XML.
subresults gets initialized with the actual data from the XML (from items inside findItems()).

[Dr-Blank]

is it possible to load the other MediaContainer attributes as well?

06819fa solves this

test fails seems unrelated