Allow specifying the final CB json file size limit

[ameshkov]

We're facing an issue with Safari not being able to accept content blockers larger than some specific size limit. We need to allow specifying the maximum size limit (size means the final JSON size):
AdguardTeam/AdguardForiOS#2188 (comment)

Currently, it hits the 24MB limit pretty easily when the JSON file is larger than 11MB.

Here's what I suggest:

1. Allow specifying the upper limit for the final size of the JSON file. Discard all rules that make the JSON file bigger than this limit.
2. Experiment with different size limits.