Consolidate OpenVINO supported OPs into frontend op_table

[cavusmustafa]

The OpenVINO backend maintains hardcoded static sets of supported ops in ggml_backend_openvino_device_supports_op (lines 949–966 of ggml/src/ggml-openvino/ggml-openvino.cpp):

static std::set<ggml_type> supported_types{ ... };
static const std::set<ggml_op> supported_ops{ ... };
static const std::set<ggml_unary_op> supported_unary_ops{ ... };
static const std::set<ggml_glu_op> supported_glu_ops{ ... };

The frontend already has ggml/src/ggml-openvino/openvino/op_table.cpp via get_supported_ops(). These two lists have already drifted:

Op	op_table.cpp	Backend supported_ops
GGML_OP_ADD1	yes	missing
GGML_OP_DIV	yes	missing
GGML_OP_SUB	yes	missing
GGML_OP_SOFT_MAX	yes	commented out
GGML_OP_CONT	yes	commented out
GGML_OP_NONE	absent	present (special passthrough)

This means ops like GGML_OP_ADD1, GGML_OP_DIV, and GGML_OP_SUB have frontend translators but will never be dispatched to OpenVINO because the backend's supports_op check rejects them first.

Proposed change

Update ggml_backend_openvino_device_supports_op in ggml/src/ggml-openvino/ggml-openvino.cpp to derive support information from get_supported_ops() (defined in openvino/op_table.h / openvino/op_table.cpp) instead of maintaining separate hardcoded sets.

Why this matters

• Establishes a single source of truth for OpenVINO op support
• Fixes existing silent bugs: GGML_OP_ADD1, GGML_OP_DIV, GGML_OP_SUB have translators but are never dispatched
• Reduces maintenance burden when adding new ops to the frontend
• Prevents future frontend/backend support-list divergence

Acceptance criteria

• Hardcoded static supported-op sets in ggml_backend_openvino_device_supports_op are removed or replaced by op_table-driven logic
• Backend op support checks resolve through get_supported_ops() from openvino/op_table.cpp
• Intentional exclusions (GGML_OP_NONE, GGML_OP_SOFT_MAX, GGML_OP_CONT) are explicitly handled with comments explaining why
• No behavioral regressions in currently supported OpenVINO ops
• CI Tests passing