feat: migrate auth0mock from Node.js to Go

Refactor the application to a Go-based architecture for improved
performance and maintainability. Replace the Dockerfile to utilize a
multi-stage build process, enhancing image efficiency. Implement
comprehensive session store tests to ensure reliability and create
new OAuth handlers for managing authentication efficiently. Update 
documentation to reflect these structural changes.

handlers/templates/login.html

@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
+    <title>Auth</title>
+    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">
+  </head>
+  <body>
+    <div class="container">
+      <form method="post" action="/code">
+        <div class="card" style="width: 18rem; margin-top: 2rem;">
+          <div class="card-body">
+            <h5 class="card-title">Login</h5>
+            <div class="form-group">
+              <label for="email">Email</label>
+              <input type="text" name="email" id="email" class="form-control">
+            </div>
+            <div class="form-group">
+              <label for="password">Password</label>
+              <input type="password" name="password" id="password" class="form-control">
+            </div>
+            <div class="form-check">
+              <input class="form-check-input" type="checkbox" name="admin" value="true" id="admin">
+              <label class="form-check-label" for="admin">
+                Admin
+              </label>
+            </div>
+            <button type="submit" class="btn btn-primary mt-3">Login</button>
+            <input type="hidden" value="{{.Redirect}}" name="redirect">
+            <input type="hidden" value="{{.State}}" name="state">
+            <input type="hidden" value="{{.Nonce}}" name="nonce">
+            <input type="hidden" value="{{.ClientID}}" name="clientId">
+            <input type="hidden" value="{{.CodeChallenge}}" name="codeChallenge">
+          </div>
+        </div>
+      </form>
+    </div>
+  </body>
+</html>