Issue 6830 - Generate CSV only for changed strings, import only translations and modularize code

For main information/background about current PR see -> https://gitlab.com/eyeo/adblockplus/adblockplusui/issues/148

This PR also contains changes for -> https://gitlab.com/eyeo/adblockplus/adblockplusui/issues/74 (As @ThomasGreiner asked me to include that as well)

Notes: Some of the changes have already reviewed, if a reviewer wish to check whether the implementation is already reviewed or not, you can just check the old/initial monolithic implementation file.