[BSP] TaskFinish is never sent

[srdo]

We have started sending TaskStart here https://github.com/lihaoyi/mill/blob/master/bsp/src/mill/bsp/Utils.scala#L32.

The associated TaskFinish should be getting sent from here https://github.com/lihaoyi/mill/blob/master/bsp/src/mill/bsp/BspLoggedReporter.scala#L133

It seems like printSummary is not invoked in many cases, leaving tasks unfinished from the IDE's point of view.

To reproduce check out master, build with ci/publish-local.sh, copy the generated file to your Mill download directory, update .mill-version to mill-release, open Mill with Intellij and press the build button. The build will complete, but lots of tasks in the build overview will appear to still be running.

I've attached a screenshot of what this looks like.