* Adding a timeout and retry to upload results step.

* Adding tests for retries and timeout.

* Adding async to call

* Fixing sleep to trigger the timeout, and adding addition timeout test.

* Fixing minor typo.

* Fixing some minor flutter style issues.
Co-authored-by: yusufm <mohsinally@google.com>

Some runs of DeviceLab performance tests are run without a gitBranch option, but
still must save their results to a local file.

(Attempt to reland #85993)

This reverts commit 2175e64e.

Migrate core devicelab framework to null safety.

This reverts commit 2be0d57f.

This reverts commit 9846fa51.

This reverts commit 05d55157.

This reverts commit ef2879a4.

This adds avoid_dynamic_calls to the list of lints, and fixes all instances where it was violated.

Importantly, this lint is NOT turned on for flutter/packages/test, because those changes are happening in another PR: #84478

This reverts commit 0c9781e3.

This reverts commit 93fb2586.