feat: allow :algolia settings to be either static or dynamic

[Jordan-Kowal]

New

The Algoliax.Indexer now supports dynamic definition for the :algolia settings. It can supports 2 types of configurations:

• (Existing) Keyword list
• (New) Name of a 0-arity function that returns a keyword list

defmodule People do
  use Algoliax.Indexer,
    index_name: :people,
    object_id: :reference,
    schemas: [People],
    algolia: :runtime_algolia

  def runtime_algolia do
    [
      attribute_for_faceting: ["age"],
      custom_ranking: ["desc(updated_at)"]
    ]
  end
end

Also added 2 new exceptions for the :algolia configuration: InvalidAlgoliaSettingsFunctionError and InvalidAlgoliaSettingsConfigurationError

Other changes

Existing direct calls to Algoliax.Settings.replica_settings/2 will still work but will not benefit from
the dynamic :algolia configuration. Please use Algoliax.Settings.replica_settings/3 instead.

[Jordan-Kowal]

This code is not used anywhere (except in test) but it is public, so I'm not sure if I can just delete it 💀

[Jordan-Kowal]

(nit) I simply fixed the settings configuration, but it has 0 impact since those keys are not used by the functions tested in this module