GH-135: Implement ability to only include direct dependencies

[ascopes]

A component that makes up a small part of the overall solution for GH-135, by providing the initial ability to not include transitive dependencies implicitly, only directly specified ones.

This is achieved via a new parameter dependencyResolutionDepth which will be set to TRANSITIVE by default to exhibit the current resolution behaviour. It can optionally be set to DIRECT instead to allow only adding explicitly included dependencies to the protopath.

The change will be complimented in a future set of PRs with the ability to add dependencies without making them visible to the Java compiler, and the ability to disable reading the Java classpath dependencies at all to enable more control over how the dependency mechanism works.

[codecov]

Codecov Report

Attention: Patch coverage is 77.27273% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 82.49%. Comparing base (8de0163) to head (53137d8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #139      +/-   ##
==========================================
- Coverage   82.67%   82.49%   -0.17%     
==========================================
  Files          24       25       +1     
  Lines         819      828       +9     
  Branches       54       55       +1     
==========================================
+ Hits          677      683       +6     
- Misses        122      124       +2     
- Partials       20       21       +1     

Files	Coverage Δ
...opes/protobufmavenplugin/AbstractGenerateMojo.java	82.26% <100.00%> (+0.30%)	⬆️
...enplugin/dependency/DependencyResolutionDepth.java	100.00% <100.00%> (ø)
...tobufmavenplugin/dependency/JvmPluginResolver.java	85.42% <100.00%> (ø)
...avenplugin/dependency/PlatformArtifactFactory.java	100.00% <ø> (ø)
...tobufmavenplugin/generate/SourceCodeGenerator.java	90.70% <100.00%> (+0.23%)	⬆️
...plugin/dependency/MavenDependencyPathResolver.java	80.56% <58.34%> (-7.32%)	⬇️