feat: Elixir Phoenix example

[tobbbles]

Create a basic example for Ory Network implemented with Phoenix Framework, implementing basic user flows.

Highlights how to use the ory_client Elixir package from https://github.com/ory/sdk and implement it in a simple web application.

Related Issue or Design Document

Checklist

• I have read the contributing guidelines and signed the CLA.
• I have referenced an issue containing the design document if my change introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security vulnerability.
  If this pull request addresses a security vulnerability,
  I confirm that I got approval (please contact security@ory.sh) from the maintainers to push the changes.
• I have added tests that prove my fix is effective or that my feature works.
• I have added the necessary documentation within the code base (if appropriate).

Further comments

This example is definitely not a fully fledged implementation, and is (currently) missing the following:

• Settings UI
• Verification UI
• Recovery UI
• Proper Error handling

I am also debating on whether to take my current UI Node implementation and break this out into it's own package; for others to use to easily implement forms in Phoenix, similar to the https://github.com/ory/elements component library.

[tobbbles]

Waiting on ory/sdk#283

[tobbbles]

Update: v7.0.0 of the openapi-generator got released with a breaking change to the Elixir client by moving to a better serialization library. I'll wait until the SDK is updated with that, and then re-jig the example

[CLAassistant]

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[tobbbles]

Update: v7.0.0 of the openapi-generator got released with a breaking change to the Elixir client by moving to a better serialization library. I'll wait until the SDK is updated with that, and then re-jig the example

Upstream SDK PR is opened - ory/sdk#315