Format Comments Consistently in P4C.

[sumit7754]

This issue aims to address the lack of consistency in comment formatting across the core parts of the P4C compiler. Following a discussion in #4563, it has been suggested to adopt a unified commenting style: using triple slashes (///) for documenting functions and classes, and double slashes (//) for comments within code. This approach aligns with the recommendation provided in the Doxygen documentation.