Add devtools tests

[Piinks]

Add the flutter/devtools test suite for checking against changes in flutter/flutter

Fixes flutter/devtools#4433

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read the Flutter Style Guide recently, and have followed its advice.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

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[Piinks]

For this, I will need to write a custom script in devtools to run the tests. I will follow up on this tomorrow

[kenzieschmoll]

Is this typically a single person or a google group? If it does need a primary POC then that is fine to be me but can we add a secondary contact [email protected]?

[Piinks]

Definitely, I'll update this.

[Piinks]

Hmm... Looks like a bunch of tests are timing out. and not all of the expected mocks are created by the generate script.

[Piinks]

Closing since the devtools tests aren't working in this environment as expected right now.