Add install/uninstall/activate/deactivate hooks to pub

[DartBot]

<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="96" height="96"hspace="10"> Issue by sethladd
Originally opened as dart-lang/sdk#21584

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To repro:

pub global activate stagehand
mkdir empty
cd empty
stagehand webapp
  (say Y to analytics)
pub global deactivate stagehand

cat ~/.stagehand

Expected: ~/.stagehand file is deleted (or, a notice is sent to stagehand that the package is getting deleted)

Actual: apparently (?) no signal on uninstall

[DartBot]

<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="48" height="48"hspace="10"> Comment by sethladd

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If there's a lifecycle callback that pub is sending, and that stagehand is not listening to, please let us know and then close this issue. :) Thanks for taking a look!

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

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Pub doesn't currently support any package hooks of any kind, but we may in the future. I'm retargeting this issue to that.

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Removed Priority-Unassigned, Pub-Global labels.
Added Priority-Low label.
Changed the title to: "Add install/uninstall/activate/deactivate hooks to pub".

[DartBot]

<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="48" height="48"hspace="10"> Comment by sethladd

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sgtm

[matanlurey]

We are no longer supporting transformers or pub serve/build going forward (this tooling has moved elsewhere into the https://github.com/dart-lang/build repository and https://github.com/dart-lang/webdev CLI) so a fix for this is not planned.

We'll be updating the tooling section of the Dart website in the coming weeks with more formal documentation on how to get started.