Problem: protobuf message urls should not change

[yihuang]

Solution:

• revert the package name change introduced in #1023.
• don't remember why we have to change it there, but it seems not nesserary, revert it to keep it backward compatible.
• change proto file folder structure to match the package name instead.

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Thank you for your code, it's appreciated! :)

[mmsqe]

I rmb since proto paths need to match folder paths

[yihuang]

I rmb since proto paths need to match folder paths

yeah, I also changed the folder, it'll be headache to break the msg urls.

[ankushgoel27]

/runsim test