Add uniqueness check to "Create project" command (#5100)

* Add failing playwright test

* Make create generate a unique name if the given one collides

* Add a new consolidated getUniqueProjectName function with tests

* Use getUniqueProjectName

* Replace "New project" button text with "Create project"
cc @pierremtb

* Extend the e2e test to show the incrementing behavior
cc @lf94

src/routes/Home.tsx

@@ -148,7 +148,7 @@ const Home = () => {
                 }}
                 data-testid="home-new-file"
               >
-                New project
+                Create project
               </ActionButton>
             </div>
             <div className="flex gap-2 items-center">