Deprecate methods and packages that are no longer relevant

[krzysu]

As we prepare for future version of the library, we should start marking functions and modules that we no longer plan to support, signaling to users that they should transition away from using them. Communicating this early will help avoid confusion later.
As I understand, there are functions inherited from Web3.js v1 that were kept for compatibility but are no longer in use or relevant. Additionally, some packages, like web3-eth-ens, shouldn’t be recommended anymore as they are outdated.

It becomes straightforward if we have a clear list of functions that we no longer plan to support.

/**
 * @deprecated This function will be removed in the next major release. Use `newFunction()` instead.
 */
function oldFunction() {
  //
}