Clean how the project deal with DI

[lyrixx]

TODO

• [x] Externalize all "factory" to a proper class
• [x] The client use the Factory now, but all methods are deprecated
• [x] Introduce IndexNameMapper to map an index to a class (and deal with "pure" index name)
• [x] Introduce ContextBuilderInterface to retrive to build a context for the serializer
• [x] Break many inderections, and try to reduce the dependency on the Client
• [x] Fixed tests
• [x] Update README
• [x] CHANGELOG

[lyrixx]

Looks good. Not a fan of all the constants being in the Factory class, if this class is only supposed to help peoples that don't use DIC? Feels likes unnecessary move, could you elaborate on the motivations behind this change?

To me it's odd to define constants in a class, and use theme in another class (less context switch). More over, only one use statement is needed with all in the same place. And finally, Why would we set these constant in the Client? It has nothing to do with the client.

The original code made sure to never override Elastica __construct methods, to be as much compatible as possible and compatible with future versions of Elastica. Do you think that was unnecessary precaution?

I agree with you. I'm not very confortable with that either. But since elastically extends elastica, we should not avoid to override constructor : 1/ it blocks us for future developments 2/ we write more complexe code. So I override constructor, and I pretty confident because 1/ semver exists, and I hope elastica respect it 2/ we have tests (that are run each week whatever happen).

I'm not able to test it right now, but I'm looking forward the README change to see the impact ^^

I'll do that right now :)

[lyrixx]

The PR is ready ✅