Visually improve `inspect` when used for multiple tasks

[lefou]

Often, the easiest way to use inspect for nested tasks is to prepend it with __..

> mill inspect __.publishM2Local
contrib.artifactory.publishM2Local(PublishModule.scala:435)
    Publish artifacts to a local Maven repository.
    
    @param m2RepoPath The path to the local repository  as string (default: `$HOME/.m2/repository`).
    If not set, falls back to `maven.repo.local` system property or `~/.m2/repository`
    @return [[PathRef]]s to published files.

    --m-2-repo-path <str>

Inputs:
    contrib.artifactory.jar
    contrib.artifactory.sourceJar
    contrib.artifactory.docJar
    contrib.artifactory.extraPublish
    contrib.artifactory.artifactMetadata
    contrib.artifactory.pom

contrib.buildinfo.publishM2Local(PublishModule.scala:435)
    Publish artifacts to a local Maven repository.
    
    @param m2RepoPath The path to the local repository  as string (default: `$HOME/.m2/repository`).
    If not set, falls back to `maven.repo.local` system property or `~/.m2/repository`
    @return [[PathRef]]s to published files.

    --m-2-repo-path <str>

Inputs:
    contrib.buildinfo.jar
    contrib.buildinfo.sourceJar
    contrib.buildinfo.docJar
    contrib.buildinfo.extraPublish
    contrib.buildinfo.artifactMetadata
    contrib.buildinfo.pom

contrib.codeartifact.publishM2Local(PublishModule.scala:435)
...

Often, this matches multiple tasks (in this case 86!!) but the task documentation and definition side is the same.

We should be able to consolidate this output, e.g. by just displaying the documentation once.