fix(api): isolate drive.spec.ts's files folder from the real drive

drive.spec.ts already isolates itself into a unique, timestamped
tmpFolder for getSasjsRootFolder()/getUploadsFolder(), cleaned up via
afterAll(() => deleteFolder(tmpFolder)). But getFilesFolder() - what
nearly every test in this file actually writes to - resolves through
a separate, unmocked function (getSasjsDriveFolder()/process.driveLoc),
so every run left real files/folders (e.g. 'level1', 'my/path/...')
behind in the shared api/sasjs_root/drive/files, causing later runs
to fail: folder-listing tests saw stale entries, and file-creation
tests got 409 Conflict against files a previous run already created.

Mock getFilesFolder() the same way getUploadsFolder() already is, so
it resolves inside the same isolated tmpFolder and gets cleaned up
by the existing afterAll. Verified by running the suite twice in a
row from a clean slate: both runs pass, and the real sasjs_root/drive
is never touched.

api/src/routes/api/spec/drive.spec.ts

@@ -28,6 +28,15 @@ jest
   .spyOn(fileUtilModules, 'getUploadsFolder')
   .mockImplementation(() => path.join(tmpFolder, 'uploads'))
 
+// getFilesFolder() resolves via getSasjsDriveFolder()/process.driveLoc, a
+// separate root from getSasjsRootFolder()/process.sasjsRoot above - without
+// this, every test in this file that creates content under the drive (e.g.
+// 'level1', 'my/path/...') writes into the real, shared sasjs_root/drive
+// instead of this run's isolated tmpFolder, leaking state into later runs.
+jest
+  .spyOn(fileUtilModules, 'getFilesFolder')
+  .mockImplementation(() => path.join(tmpFolder, 'drive', 'files'))
+
 import appPromise from '../../../app'
 import {
   UserController,