Added a task to check for unpublished artifacts

[lefou]

Staged Publishing via Sonatype Nexus fail occasionally. Sometime, the staging process was complete, sometimes not. Since subsequence publish-jobs fail for previously properly published artifacts, it's not easy to tell, which CI publish jobs in failure state need a restart.

Therefore you can use theis new command to check for already published modules.

Example: Some modules where published, some not

In that case, you need to find that shard, which published these modules. In the CI log, go to the last lines, where all published modules are printed. If you found the correct shard, restart it.

> mill checkPublishedArtifacts --artifacts __.publishSelfDependency --version 3.0.0-M1-3-47512ee8 --ttl "1 sec"
...
1 targets failed
checkPublishedArtifacts Missing 46 of 276 published artifacts: 
- com.lihaoyi:ammonite-compiler-interface_3.3.0:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-compiler-interface_3.3.1:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-compiler-interface_3.3.2:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-compiler-interface_3.3.3:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-compiler_3.2.2:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-compiler_3.3.0:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-compiler_3.3.1:3.0.0-M1-3-47512ee8
...
- com.lihaoyi:ammonite-sshd_3.3.2:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-sshd_3.3.3:3.0.0-M1-3-47512ee8
- com.lihaoyi:ammonite-terminal_3:3.0.0-M1-3-47512ee8

Example: All modules published successfully

> mill show checkPublishedArtifacts --artifacts __.publishSelfDependency --version 3.0.0-M1
[1/1] show 
[1/1] show > [2485/2485] checkPublishedArtifacts 
"All artifacts published for version 3.0.0-M1"

Example: All modules not published

> mill show checkPublishedArtifacts --artifacts __.publishSelfDependency --version 3.0.0-M2
[1/1] show 
[1/1] show > [2485/2485] checkPublishedArtifacts 
1 targets failed
show 1 targets failed
checkPublishedArtifacts All artifacts missing for version 3.0.0-M2