[Data] Add optional blocksize_elements to BlockingParameters

[rfsaliev]

This pull request enhances the flexibility and predictability of blocked data structures by introducing explicit control over the number of elements per block (blocksize_elements) in addition to the existing byte-based blocking (blocksize_bytes). It also improves test coverage to verify the new behavior and edge cases.

Blocking parameter improvements:

• Added an optional blocksize_elements field to the BlockingParameters struct, allowing users to specify the number of elements per block directly. If set, this takes precedence over blocksize_bytes when determining block size. (include/svs/core/data/simple.h)

Testing and validation:

• Added test to demonstrate the pitfalls of relying solely on blocksize_bytes for memory prediction.
• Extended unit tests to cover scenarios where blocksize_elements is set, including checks for correct block size selection and memory consumption predictions.
  (tests/svs/core/data/block.cpp)

[Copilot]

Pull request overview

Adds an element-count-based blocking option to make blocked dataset sizing more predictable across element types/dimensions, while preserving the existing byte-based configuration.

Changes:

• Extended svs::data::BlockingParameters with optional blocksize_elements (takes precedence when present).
• Updated blocked SimpleData construction to compute blocksize_ from blocksize_elements when provided, otherwise fall back to blocksize_bytes.
• Added unit tests (with a recording allocator) to demonstrate blocksize_bytes pitfalls and validate deterministic behavior with blocksize_elements.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
include/svs/core/data/simple.h	Adds blocksize_elements and updates blocked SimpleData to prefer explicit element-based block sizing.
tests/svs/core/data/block.cpp	Adds tests and a recording allocator to validate new block sizing behavior and memory prediction differences.

[rfsaliev]

/intelci