[WIP] Subscription management (#63)

* Basic UI

@luketainton please edit lines 120-140 on the editsub and managesub files

* ✨ Add subscription management

Signed-off-by: Luke Tainton <luke@tainton.uk>

* ✨ Add subscription management

Signed-off-by: Luke Tainton <luke@tainton.uk>

* 🐛 Fix incorrect POST variable and add foreach()

Signed-off-by: Luke Tainton <luke@tainton.uk>

* 🎨 Fix file names and add link on view.php

Signed-off-by: Luke Tainton <luke@tainton.uk>

Co-authored-by: Alexander Davis <alex@adcm.uk>

app/includes/app_functions.php

@@ -1,4 +1,17 @@
 <?php
+  function get_all_users($db) {
+    try {
+      $stmt = "SELECT * FROM users";
+      $sql = $db->prepare($stmt);
+      $sql->execute();
+      $sql->setFetchMode(PDO::FETCH_ASSOC);
+      $result = $sql->fetchAll();
+    } catch (PDOException $e) {
+      echo("Error: " . $e->getMessage());
+    }
+    return $result;
+  }
+
   function get_user_name($db, $user_uuid) {
     try {
       $stmt = "SELECT given_name, family_name FROM users WHERE uuid=:uuid";