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/lib/desktopFS.test.ts

@@ -0,0 +1,58 @@
+import { getUniqueProjectName } from './desktopFS'
+import { FileEntry } from './project'
+
+/** Create a dummy project */
+function project(name: string, children?: FileEntry[]): FileEntry {
+  return {
+    name,
+    children: children || [
+      { name: 'main.kcl', children: null, path: 'main.kcl' },
+    ],
+    path: `/projects/${name}`,
+  }
+}
+
+describe(`Getting unique project names`, () => {
+  it(`should return the same name if no conflicts`, () => {
+    const projectName = 'new-project'
+    const projects = [project('existing-project'), project('another-project')]
+    const result = getUniqueProjectName(projectName, projects)
+    expect(result).toBe(projectName)
+  })
+  it(`should return a unique name if there is a conflict`, () => {
+    const projectName = 'existing-project'
+    const projects = [project('existing-project'), project('another-project')]
+    const result = getUniqueProjectName(projectName, projects)
+    expect(result).toBe('existing-project-1')
+  })
+  it(`should increment an ending index until a unique one is found`, () => {
+    const projectName = 'existing-project-1'
+    const projects = [
+      project('existing-project'),
+      project('existing-project-1'),
+      project('existing-project-2'),
+    ]
+    const result = getUniqueProjectName(projectName, projects)
+    expect(result).toBe('existing-project-3')
+  })
+  it(`should prefer the formatting of the index identifier if present`, () => {
+    const projectName = 'existing-project-$nn'
+    const projects = [
+      project('existing-project'),
+      project('existing-project-1'),
+      project('existing-project-2'),
+    ]
+    const result = getUniqueProjectName(projectName, projects)
+    expect(result).toBe('existing-project-03')
+  })
+  it(`be able to get an incrementing index regardless of padding zeroes`, () => {
+    const projectName = 'existing-project-$nn'
+    const projects = [
+      project('existing-project'),
+      project('existing-project-01'),
+      project('existing-project-2'),
+    ]
+    const result = getUniqueProjectName(projectName, projects)
+    expect(result).toBe('existing-project-03')
+  })
+})