[fix][elixir] wrong typespec generation for all-of with single ref

[efcasado]

Description

This PR addresses the issue reported in #21135 - ie. an issue with the generated typespecs that would prevent some generated clients from compiling; but it also introduces the following changes:

• Remove dead code
• More idiomatic type mappings and language-specific types
• Refactor type detection and typespecs generation to improve code re-usability and mantainability

All in all, this should contribute to make the Elixir generator easier to extend and more maintainable.

As usual, curious to hear your thoughts @mrmstn, @wing328 🙂

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[efcasado]

Now, we are truly mapping to Elixir built-in types.

[efcasado]

This is more idiomatic and allows us to better identify what schemas may need a custom model doing something along the lines of languageSpecificPrimitives.contains(type)

[efcasado]

With better type mappings, code like this one (which was incomplete and should have also included other types such as Map, etc.) is no longer necessary.

[efcasado]

This method wasn't used anywhere in the generator.

[efcasado]

number() is more accurate since we are not specifying any format in the OAS. number() captures whole numbers and floating point numbers (see here).

[efcasado]

I think this is quite a milestone 😄

==> cloudflare
Compiling 5606 files (.ex)
Generated cloudflare app

Now, we can use the Elixir generation to build non-trivial clients (yeah, 5,606 files including model and API files). The above is the output I got when running this version on Cloudflare's official OAS (see here). This wasn't possible a few weeks ago 😄

[wing328]

nice, we will try to get it merged before the v7.13.0 release due this week