handling of versioning

[jameslamb]

@ngparas comments on #73

since there are also minor changes in scrolling between the versions i'd love if we could pull all the version-specific stuff up higher and configure w/ passing functions instead of putting internal switches like this

IMHO the best way to handle this would be to use an internal R6 object that just holds all of the version specific stuff and have that object get passed around to methods that need it (all internal). But idk...open to suggestions

[jameslamb]

Add R label since using an internal object is already how we handle this in Python.

[jameslamb]

Two years later, the code for #73 is still going strong!

from the blame:

Since we're not considering extensions to uptasticsearch and just basically keeping it working, I don't think we're ever going to refactor the internals of the R package like this issue describes. I think this can be closed.