Support configuration of index settings

[Gavrilov-Ivan]

There should be ability to configure different settings for some specific or all indices.
Parameter for specific indices should override the same parameter for all indices.

Testing:

1. Create 2 entity, configure indexes for them
2. Create Spring Bean implements IndexSettingsConfigurer
3. In configure method set value of some settings parameter (e.g. "index.mapping.total_fields.limit" = 1500) for all indexes (context.getCommonSettingsBuilder) and some another value of the same parameter (e.g. "index.mapping.total_fields.limit" = 2000) for one of your indexed entity directly (context.getEntitySettingsBuilder(SomeEntity.class))
4. ER: check metadata of both indexes - settings contain parameter with correct value (1500 and 2000)

[maistrenkoIulia]

verified