net/ns3: simplify

• Convert to USES=waf (respects MAKE_JOBS_NUMBER)
• Convert to option helpers
• Define WRKSRC_SUBDIR after adjusting patches
• Drop/rename common option and their descriptions
• pkg-plist: rename WITH_DEBUG to DEBUG_SUFX to avoid confusion
• pkg-plist: define VERSION to avoid churn on updates
• post-install: compress multiple sh(1) loops via find(1) expressions

PR: 208146
Approved by: Nikola Kolev (maintainer)