This commit restores the read-only `finalName` so that its value can
be lazily resolved against `${project.build.finalName}`.

While doing the evaluation ourselves and not relying on a dedicated
field at all would have been better, the evaluation increased the
number of required dependencies for no good reason.

IDEs should not offer auto-completion for that read-only field and it
is not published in the generated site either.

Closes gh-16456