Use project name in generated Apache NOTICE

[wilx]

Summary

Use the Maven project name as the default project name in notices generated by
ApacheNoticeResourceTransformer.

The transformer previously initialized projectName to an empty string and the
mojo never supplied the injected MavenProject. Consequently, configuring the
transformer without an explicit <projectName> produced a blank generated
NOTICE header even when the POM had a nonblank <name>.

ShadeMojo now supplies MavenProject#getName() when the transformer project
name is unset and the Maven project name is neither null nor blank. Explicit
transformer configuration remains authoritative, and a missing or blank Maven
project name preserves the previous empty behavior.

The change includes unit coverage for the fallback rules, a failing-first
integration test for the generated NOTICE, and documentation of the default.

Fixes #742.

Validation

• mvn -Prun-its clean verify: 74 unit tests and 84 integration projects
  passed; two projects were skipped by their JRE-version conditions.
• JDK 21 mvn test: 74 tests passed.
• Maven 4 built the isolated regression project with the branch plugin and
  generated the expected NOTICE header.
• mvn site passed.

Following this checklist to help us incorporate your
contribution quickly and easily:

• Make sure there is a JIRA issue filed
  for the change (usually before you start working on it). Trivial changes like typos do not
  require a JIRA issue. Your pull request should address just this issue, without
  pulling in other changes.

  This change is tracked by GitHub issue #742; no separate JIRA issue was opened.
  

• Each commit in the pull request should have a meaningful subject line and body.

• Format the pull request title like [MSHADE-XXX] - Fixes bug in ApproximateQuantiles,
  where you replace MSHADE-XXX with the appropriate JIRA issue. Best practice
  is to use the JIRA issue title in the pull request title and in the first line of the
  commit message.

  The title uses `#742`, the repository's GitHub tracking issue.
  

• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.

• Run mvn clean verify to make sure basic checks pass. A more thorough check will
  be performed on your pull request automatically.

• You have run the integration tests successfully (mvn -Prun-its clean verify).

If your pull request is about ~20 lines of code you don't need to sign an
Individual Contributor License Agreement if you are unsure
please ask on the developers list.

To make clear that you license your contribution under
the Apache License Version 2.0, January 2004
you have to acknowledge this by using the following check-box.

• I hereby declare this contribution to be licenced under the Apache License Version 2.0, January 2004

• In any other case, please file an Apache Individual Contributor License Agreement.