Port the IT scripts from BeanShell to Groovy

[slachiewicz]

Ports the 108 BeanShell IT scripts under src/it/projects to Groovy, keeping the same checks. 101 were already valid Groovy. The seven that changed: two dead printlns of a variable no script ever declared (BeanShell treats an unbound name as void, Groovy throws) are removed (basic-features/add-classpath, mojo-configuration/manifest-with-customEntry-manifest-file); a same-scope String line redeclaration becomes an assignment (metaInf-spring-aggregation); a File[] x = { … } initialiser becomes a list literal (dep-transfilter-wildcard-massembly544); two literal ${…} assertions use single quotes so Groovy does not interpolate them (filters-defined-in-build, massembly-285-assembly); and BeanShell's basedir == void unset check becomes !binding.hasVariable('basedir') (dependencySet-projectArtifactNotIncluded). The rename is a separate commit so the port reads as a diff. Part of apache/maven#13207.

Three of the scripts never run under -Prun-its and are ported blind: two are submodules no pomInclude matches (massembly-285-assembly, multimodule-filteredFileSet/child) and depSet-transFromProfile is in pomExcludes.

Verified: mvn verify -Prun-its -Dinvoker.test=<all 105 runnable IT projects> in five batches → 26 + 26 + 26 + 26 + 6 passed, 0 failed (each batch includes the it-project-parent setup project).