Eliminate the use of the cv namespace

[advait-0]

Users especially those new to C++ often face confusion and difficulties in understanding the proper usage of OpenCV classes due to the common practice of using the cv namespace. To improve clarity and encourage best practices, I think it is suitable to eliminate the use of the cv namespace in our examples.

Possible solution to this problem could be:

• Encouraging Explicit Namespace Usage: Update documentation and examples to explicitly use the cv:: prefix for OpenCV classes (e.g., cv::Mat, cv::VideoCapture) instead of relying on the cv namespace. This will also allow users to have a better understanding of the working of C++ as using namespaces abstracts some stuff.

[AryanNanda17]

I will start working on this issue and will do the PR by midnight.

[AryanNanda17]

@advait-0, there are already some existing PRs that should be merged before I do the namespace change else the test cases would fail because of merge conflicts.