[Tensor] Operational Improvements and Functionality Simplification

[Tensor] Operational Improvements and Functionality Simplification

This commit moves several operations implementations to each Tensor class for easier management.
This allows users to create a new data type Tensor without unnecessary modification to the Tensor class.

**Changes proposed in this PR:**
- static function Tensor::cat() uses each tensor's member function concat().
- Tensor::copy() logic is simplified by not differentiating by its data type.
- Tensor::copy_with_stride() uses an internal function to operate.

**Self-evaluation:**
1. Build test: [X]Passed [ ]Failed [ ]Skipped
2. Run test:   [X]Passed [ ]Failed [ ]Skipped

Signed-off-by: Donghyeon Jeong <dhyeon.jeong@samsung.com>