[2.0.0] Rename Config to CacheManagerConfig

[LasseRosenow]

🏗 Enhancement Proposal

Since version 2.0.0 the flutter_cache_manager exports a class called Config. This name is very general and causes problems in all my projects because I have a general Config class.

I think the name Config is a very bad choice, as it is way to general. So I propose renaming it to CacheManagerConfig to prevent conflicts like these to occur.

I know that it is possible to work around this issue by using import a as b, but I think this should be avoided to make the development process more easy.

Also the name CacheManagerConfig would be much more intuitive to use, as you usually wouldn't expect to have a class called Config, but rather somthing like CacheManager*** while writing your code with intellisense.

[renefloor]

Yes I agree Config is not the best name.