chore: add deprecation message to 'pipe-naming' rule

[rafaelss95]

Once someone try to use this deprecated rule, it'll show a warning like:

pipe-naming is deprecated. Message here

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Not sure if it's the best message, but I've picked it in #519 (comment).

[rafaelss95]

@mgechev @wKoza while I do understand why it's deprecated, I can still see useful things in it such as enforcing prefixes like we do for component and directive.

Can't we just deprecate the actual configuration?

---

A new configuration could be like this:

{
  "rules": {
    "pipe-naming": [true, "^ngx?[A-Z]+"]
    // or less generic, as an array
    "pipe-naming": [true, "ng", "ngx"]
  }
}

[mgechev]

@rafaelss95 I like the regex config:

"pipe-naming": [true, "^ngx?[A-Z]+"]

It'll make more sense to rename the rule. If we have a rule with the same name but different semantics we'll create a lot of confusion.

[rafaelss95]

Does it makes sense to create another rule now? Or better wait for complete removal of this?