Feature: Add PlexApi class for dealing with Plex Api fetching and caching

[glensc]

Extracted from #122

The purpose of the API class is to make API access fluent, without having to dea with cache_disabled wrapping or thinking if method calls should be cached.

This class makes heavy use of decorators to simplify the code itself.

[glensc]

Another extract, only implemented few methods, to get acquainted with the usage pattern. so the next method implementation would go smoother.

[glensc]

@twolaw @Taxel can we get this merged? this and tons of other PR's prevent me from making more changes. and I don't want to make the changes to the old codebase where everything is in one big unmaintainable file.

[glensc]

@twolaw @Taxel since the review and approval is taking way too long, and @Taxel doesn't respond to lift the 1 approve the rule, perhaps I merge the new things to "develop" branch, and then for release use the existing "master" branch? i.e use the git-flow model.

I have tons of things I want to accomplish, but getting things merging here is very painful here.

I'm still struggling here to get changes I made 25 days ago:

• Move code to plex_trakt_sync module #116 it's the first PR created in sequence.

@twolaw are you ok with this?

[glensc]

also, can't even merge bugfixes:

• Fix config initialization recursive loop on first run #155 (comment)

maybe besides the "develop" branch, switch to "main" branch, until @Taxel is able to remove the 1 approval rule.

[glensc]

merging to main to get things going:

• Taxel: Change default branch to be main #162