🚀 [Hacktoberfest] Elixir - Create a new GraphQL endpoint

### 🔖 Feature description

Create a new GraphQL endpoint

### 🎤 Why is this feature needed ?

creating a GraphQL endpoint alongside a REST endpoint can provide more flexibility, efficiency, and developer-friendly features, making it a valuable addition, especially if we want to offer improved data fetching capabilities and support evolving client requirements

### ✌️ How do you aim to achieve this?

It's a new feature!

- [ ] install Absinthe

- [ ] create queries and mutations for existing REST endpoints

- [ ] create a playground to GraphQL

### 🔄️ Additional Information

It's not about replacing REST entirely but providing an alternative that can coexist and complement our existing API.

### 👀 Have you spent some time to check if this feature request has been raised before?

- [X] I checked and didn't find similar issue

### 🏢 Have you read the Code of Conduct?

- [X] I have read the [Code of Conduct](https://github.com/andrgab/medirepo/blob/main/CODE_OF_CONDUCT.md)

### Are you willing to submit PR?

None