feat(client/worker): support web work in frontend with fallback (#31)

* feat(client/web): add upload mgr

* feat(uploader): move uploader to worker

* feat(upload_mgr): use native worker for uploading

* fix(upload_mgr): fix uploading stop not working

* chore(client/web): cleanups

* test(upload.worker): add unit test for upload.worker

* feat(worker): add foreground upload worker

* chore(uploader): turn down the speedup

.gitignore

@@ -7,6 +7,7 @@
 **/yarn-error
 **/public/static/**/*.js
 **/public/index.html
+**/**/*.d.ts.map
 
 # backend
 **/*/quickshare.db