Add string input type support for SparseFillEmptyRows-16

[p-wysocki]

Tickets:

• CVS-168504

Detailed Copilot summary

This pull request introduces support for string data types in the `SparseFillEmptyRows` operation across multiple components, including core functionality, tests, and plugins. The changes enhance the operation's versatility by allowing string values as inputs, outputs, and default values, along with corresponding updates to validation, execution logic, and test coverage.

Core functionality updates:

• Removed the restriction on string inputs for SparseFillEmptyRows in the TensorFlow frontend (src/frontends/tensorflow_common/src/op/sparse_fill_empty_rows.cpp).
• Added support for string data types in the execution logic of SparseFillEmptyRows (src/plugins/intel_cpu/src/nodes/sparse_fill_empty_rows.cpp).
• Extended the evaluation logic to handle string data types (src/plugins/template/backend/ops/sparse_fill_empty_rows.cpp).

Test enhancements:

• Added test cases for string data types in the C++ unit tests (src/core/tests/type_prop/sparse_fill_empty_rows.cpp).
• Updated Python tests to include string data types in parameterized tests and input preparation logic (tests/layer_tests/tensorflow_tests/test_tf_SparseFillEmptyRows.py). [1] [2]
• Introduced new test instances for string data types in CPU-specific functional tests (src/plugins/intel_cpu/tests/functional/custom/single_layer_tests/instances/common/sparse_fill_empty_rows.cpp).

Test data generation:

• Implemented specialized test parameter generation for string data types in reference tests (src/plugins/template/tests/functional/op_reference/sparse_fill_empty_rows.cpp). [1] [2]

Additional updates:

• Extended input generation logic in CPU tests to handle string values and default values (src/plugins/intel_cpu/tests/functional/custom/single_layer_tests/classes/sparse_fill_empty_rows.cpp). [1] [2] [3] [4]
• Updated Python test files to include string data types in parameterized tests (src/bindings/python/tests/test_graph/test_sparse_fill_empty_rows.py).

[rkazants]

We need to implement SparseFillEmptyRows in a different way when string tensors are in unpacked format.
This packed format not well suits GPU and NPU devices where std::string is absent.

[p-wysocki]

SparseFillEmptyRows for unpacked strings will be added as a separate operator due to otherwise convoluted API starting with #30812, but I suppose this PR stays valid? Or do we not expect regular string tensors to come?