Add tensor related data structures for the new API

Adds the following:
 - TensorDescriptor: which is responsible for holding the information
 needed to represent a tensor (e.g. shape, dimensions, etc)
 - Tensor: an aggreate object of a descriptor and a backing memory
 - TensorPack: A map of tensor that can be passed to operators as
 inputs/outputs

Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Change-Id: I02734ac6ad85700d91d6e73217b4637adbf5d177
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5260
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/common/ITensor.h b/src/common/ITensor.h
new file mode 100644
index 0000000..ee7eac7
--- /dev/null
+++ b/src/common/ITensor.h
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2021 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef SRC_COMMON_ITENSOR_H_
+#define SRC_COMMON_ITENSOR_H_
+
+#include "src/common/IContext.h"
+#include "src/common/utils/Validate.h"
+
+struct AclTensor_
+{
+    arm_compute::detail::Header header{ arm_compute::detail::ObjectType::Tensor, nullptr };
+
+protected:
+    AclTensor_()  = default;
+    ~AclTensor_() = default;
+};
+
+namespace arm_compute
+{
+// Forward declaration
+class ITensor;
+
+/** Base class specifying the tensor interface */
+class ITensorV2 : public AclTensor_
+{
+public:
+    /** Explict Operator Constructor
+     *
+     * @param[in] ctx Context to be used by the operator
+     */
+    explicit ITensorV2(IContext *ctx)
+        : AclTensor_()
+    {
+        ARM_COMPUTE_ASSERT_NOT_NULLPTR(ctx);
+        this->header.ctx = ctx;
+        this->header.ctx->inc_ref();
+    }
+    /** Destructor */
+    virtual ~ITensorV2()
+    {
+        this->header.ctx->dec_ref();
+        this->header.type = detail::ObjectType::Invalid;
+    };
+    /** Checks if a queue is valid
+     *
+     * @return True if successful otherwise false
+     */
+    bool is_valid() const
+    {
+        return this->header.type == detail::ObjectType::Tensor;
+    };
+    /** Map tensor to a host pointer
+     *
+     * @return A pointer to the underlying backing memory if successful else nullptr
+     */
+    virtual void *map() = 0;
+    /** Unmap tensor
+     *
+     * @return AclStatus A status cod
+     */
+    virtual StatusCode unmap() = 0;
+    /** Import external memory handle
+     *
+     * @param[in] handle Memory to import
+     * @param[in] type   Type of imported memory
+     *
+     * @return Status code
+     */
+    virtual StatusCode import(void *handle, ImportMemoryType type) = 0;
+    /** Get the legacy tensor object
+     *
+     * @return The legacy underlying tensor object
+     */
+    virtual arm_compute::ITensor *tensor() = 0;
+};
+
+/** Extract internal representation of a Tensor
+ *
+ * @param[in] tensor Opaque tensor pointer
+ *
+ * @return The internal representation as an ITensor
+ */
+inline ITensorV2 *get_internal(AclTensor tensor)
+{
+    return static_cast<ITensorV2 *>(tensor);
+}
+
+namespace detail
+{
+/** Check if an internal tensor is valid
+ *
+ * @param[in] tensor Internal tensor to check
+ *
+ * @return A status code
+ */
+inline StatusCode validate_internal_tensor(const ITensorV2 *tensor)
+{
+    if(tensor == nullptr || !tensor->is_valid())
+    {
+        ARM_COMPUTE_LOG_ERROR_ACL("[ITensorV2]: Invalid tensor object");
+        return StatusCode::InvalidArgument;
+    }
+    return StatusCode::Success;
+}
+} // namespace detail
+} // namespace arm_compute
+#endif /* SRC_COMMON_ITENSOR_H_ */