rchitecture: Extract the reviews aggregator and counters from MyrestHelper

Problem/Motivation

Two related groups remain in MyrestHelper. Reviews aggregation covers getReviewsAggregateRating(), getReviewsAggregateRatingByService(), getReviewsByServices(), getVideoReviewsByServices(), getReviewsByDoctor() and getReviewFrameStructure(). Counters cover getCounters(), getTermsCount(), getNodesCount(), getCountBlogs(), getPromotionsCount(), getBeforeAfterCountByService(), getDoctorsCountByService() and getServiceRelatedCounters().

Together they are around 200 lines but make nine calls into the rest of the helper, which is why issue 32 left them alone. They are also the heaviest database users in the class, so isolating them makes the caching work in issue 60 tractable.

Proposed resolution

• Extract MyrestReviewsAggregator and MyrestCounters behind interfaces.
• Resolve the outbound calls: the page URL methods now live in MyrestPageUrlResolver and can be injected; the storage accessors and getLangcode() can be duplicated cheaply.
• getChildServicesIds() is shared with the services group and needs a decision on where it belongs.
• Give both services their own cache handling rather than sharing the helper's staticCache array.

Remaining tasks

Extract both groups and add kernel tests covering the aggregate rating queries.

User interface changes

None.

API changes

New MyrestReviewsAggregatorInterface and MyrestCountersInterface. Facade methods deprecated.