[epilogue] Fix epilogue generating incorrect packages for inner classes

[SamCarlberg]

package foo;

class Outer {
  @Logged
  static class Inner {}
}

would attempt to generate a foo/Outer/InnerLogger.java file, where the Outer package name in the generated output would conflict with the Outer class name in the user source

This fixes the issue by generating files likefoo/Outer$InnerLogger.java

Resolves wpilibsuite/2025Beta#54