Use UUIDs as primary keys instead of sequential integers

[gcauchon]

📖 Description

⚠️ I am breaking up #249 in smaller chunks to simplify open discussion on the many aspect where our boilerplate project diverted from phx.new to realign our use of Phoenix, Absinthe and many libraries with the ongoing effort of the Elixir community.

We are always using UUID as primary keys, but since the boilerplate does not inclure any Ecto schema, the groundwork was never migrated back to the template project.

📝 Notes

• use ElixirBoilerplate.Schema instead of use Ecto.Schema in every schema module.
• The new settings on ElixirBoilerplate.Repo sets the key type for migrations.

🦀 Dispatch

• #dispatch/elixir

[mirego-builds]

🦀 Requesting reviewers for this pull request:

• @charlesdemers (contributor with 0 commits in the last 90 days and 2 commits overall)
• @MathieuLegault1 (reviewer for the elixir stack)