Fixed dependancies to dependencies

This was preventing resolution of modules in the form `override lazy val
foo: FooModule = new FooModule{...}`, which are necessary when you want
to override one module with another. You couldn't resolve them via
`resolve` or run them from the command line, but you could depend on
them from other modules and have then get picked up by planning logic

These turn up in Mill's own build, and I notice I couldn't resolve e.g.
`main.codesig.test.cases[callgraph-basic-1-static-method].compile`
before this PR. After this PR, I can.

Filtering out `abstract` methods in `Reflect` seems unnecessary, since
compilation checks that every method is implemented already.

Added a unit test to cover this edge case.

Pull request: #3270

Removes reference to Scala from the Intro to Mill for Java page

Just pdating the documentation to add asdf as an option to install
mill.

Pull request: #3262

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Co-authored-by: Tobias Roeser <[email protected]>

Pull request: #3267

Pull request: #3277

Simple hello-world projects using Spring Boot and Jetty. We can expand
it more in future

…ted (#3275)

Depends on com-lihaoyi/os-lib#283

This moves the subprocess stream handling logic out of
`Jvm.spawnSubprocess` and makes it apply to all `os.proc` invocations,
greatly reducing the room for error. With this, `Jvm.spawnSubprocess`
becomes a very thin wrapper around `os.proc.spawn`. We also rely
directly on OS-Lib's own pumper threads to pump to our destination,
rather than having them pump into in-memory buffers and then spawning
our own pumper threads to pump from those buffers to the destination

I spent some time looking into how to do the stdout/err handling at the
process level, but couldn't find any reasonable mechanism to do so that
allows us to preserve the ordering of the stdout/stderr. This is the
original motivation to squishing it into one stream via
`ProxyOutputStream`/`ProxyStreamPumper` and is important because
otherwise you find e.g. stack traces out of order with printlns, which
makes debugging very difficult. Might be possible using some
socket/fifo/pipe cleverness, but not as part of this PR

Added an integration test to assert on the subtleties of stdout, stderr,
and their inherited alternatives. This PR is required for the test to
pass

* ~Move `TestModule.*` dependencies to `mandatoryIvyDeps`. This better
fits what they are, since `mandatoryIvyDeps` is defined as *Mandatory
ivy dependencies that are typically always required and shouldn't be
removed by overriding*~ Hit some issues with bincompat and supers,
skipping this for now

* Alias `JavaModuleTests` to `JavaTests` (ditto for `MavenModuleTests`,
`SbtModuleTests`, etc.) for consistency with `ScalaTests`

* Specialize Intro to Mill for Java/Scala pages for each respective
audience

Pull request: #3278