Drop depenency on base64

[Earlopain]

#759 added base64 as a depenency in order to suppress a warning/error on Ruby 3.3/3.4

Since base64 is mostly just a wrapper around the pack/unpack methods it's easy to just replace.

Other gems have taken a similar approach:

• [Fix #12310] Drop base64 gem from runtime dependency rubocop/rubocop#12313
• Remove base64 dependency rack/rack#2110
• Drop runtime dependency on base64 elastic/elasticsearch-ruby#2295
• Drop base64 gem dependency socketry/protocol-http#51
• etc.

[ixti]

We probably can introduce HTTP::Utils (don't like Utils modules in general, but it seems like fitting in this case)withencode_base64method to avoid repeatingpack`. That should make code a bit better.

[tarcieri]

Or how about HTTP::Encoding, where there are probably a few other things you could stick there to provide a nicer facade for various bits in the standard library

[ixti]

Oh, yeah! HTTP::Encoding is a much better namespace.

[Earlopain]

While trying to implement this suggestion I stumbled upon a conflict with the build-in Encoding constant. Each usage of the building encoding would need to be prefixed with :: to make ruby look in the global namespace, in addition to required changes in other gems of the ecosystem like http-form-data.

I've went with Encoder instead which doesn't have such issues.

[ixti]

Just saw this comment. Hm, I don't like Encoder name though. Probably we can go with Base64 LOL:

module HTTP
  module Base64
    module_function

    def encode64(input)
      [input].pack("m0")
    end
  end

  class Request
    include Base64

    ...

      digest = encode64("#{proxy[:proxy_username]}:#{proxy[:proxy_password]}")

    ...
  end
end

[ixti]

@tarcieri WDYT?

[Earlopain]

This does get the tests all passing, however still suffer from the same (though now a bit more theoretical) problem. Other gems that extend the HTTP namespace would now get a different constant when acessing plain Base64.

Luckily the test suite exposed the problem with using Encoding. I can't say if that would be an issue with Base64.