Merged PR 16: Transform every single class components into functional component

This improve greatly the performance and the code cleaning.
It allows us to separate the inseparable class methods into modules functions

src/Components/API/api.ts

@@ -0,0 +1,30 @@
+import { Configuration } from '../../Interfaces/Configuration';
+
+/**
+ * Fetch the configuration from the API
+ * @returns {Configation} The model of the configuration for the application
+ */
+export async function fetchConfiguration(): Promise<Configuration> {
+  const url = `${import.meta.env.VITE_API_URL}`;
+  // The test library cannot use the Fetch API
+  // @ts-expect-error
+  // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
+  if (window.fetch) {
+    return await fetch(url, {
+      method: 'POST'
+    })
+      .then(async(response) =>
+        await response.json()
+      ) as Configuration;
+  }
+  return await new Promise((resolve) => {
+    const xhr = new XMLHttpRequest();
+    xhr.open('POST', url, true);
+    xhr.onreadystatechange = function() { // Call a function when the state changes.
+      if (xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
+        resolve(JSON.parse(this.responseText));
+      }
+    };
+    xhr.send();
+  });
+}