Expose functions to manually parse cookies

[bjoluc]

@bjoluc I was thinking that it would be nice if we can expose decompressFromEncodedURIComponent so that we don't need to install lz-string on our project to decode the cookie data. Is this possible ?

Originally posted by @bryantobing12 in #17 (comment)

@bryantobing12 Thanks, agree! I'd like to have two functions, one for compressed and one for non-compressed cookies. I'd also include JSON.parse in the exposed methods, unless there's a reason not to do so?

[bjoluc]

Reconsidering this in the light of #41, it may be nice to make this config-aware, something like

function getSubtreeFromCookie(middlewareConfig: NextReduxCookieMiddlewareConfig, subtree: string, context?: ...)