feat: add addCustomDomains for all platforms

[choznerol]

Allow the user to add more domains to block.

Inspired by #302, but for all 9 platforms.

TODOs

• clojure (Tests need cbdef35 to run)
• elixir
• go
• javascript
• node
• php
• python
• ruby
• rust

Questoins

[Solved] 1. In some platforms, domain list is not a mutable global variable

In some platforms, the domain list is maintained as a static property evaluated at compile-time, so the mutate global variable strategy used in ruby/python/js/php probably won't work easily.

Rust

Update: I'll try 2.

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static BLACKLIST: &'static [&'static str] = &[{{ &listSTR }}] looks static. I'm not very familiar with Rust and can only think of the below 2 strategies:

1. Refactor BLACKLIST into something mutable, like the var ( blacklist ) in go.

2. Add another mutable global variable custom_domains to augment BLACKLIST. Probably have some performance benefit over 1. ? (not sure)

Would love to know Which one is preferred, or perhaps there is another better strategy?

Elixir (and probable Clojure too)

Update: I realized this can be achieved with a simple Agent. WIP.

---

Module Attributes like @blacklist are inlined at compile time therefore immutable (ref).

From the point of view of FP, what we do in ruby/python/js/php is not pure and has global side effects:

// test/platform.node.test.js

  isValid('foo@youtube.com')
  isValid('foo@google.com')
  isValid('ok@gmail.com')

  MailChecker.addCustomDomains(['youtube.com', 'google.com'])  // Global side effect 😨

  isInvalid('foo@youtube.com')  // Same input, different result. Not pure 😨
  isInvalid('foo@google.com')
  isValid('ok@gmail.com')

I double if it is desired (or even technically feasible) to have a similar API in Elixir/Clojure. Would love to know what the desired design for Elixir/Clojure may look like.

[FGRibreau]

👋 Regarding Rust, I would store the custom domains in another list and update the isinvalid method to check both list (BLACKLIST and custom_blocked_domains)

[FGRibreau]

Thanks! Released in v4.1.0