Mark imports of removed PrimeNG modules with TODO stubs

For each import of a PrimeNG module that no longer exists in v18 (primeng/chips, primeng/tristatecheckbox, primeng/messages, primeng/dataviewlayoutoptions), replaces the broken import statement with a const <Name>: any = null; stub annotated by a TODO comment that describes the v18 replacement. Also strips the corresponding entries from @NgModule imports, declarations, and exports arrays since Angular's compiler rejects null values there. Each flagged site is also recorded in the ManualMigrationSteps data table so downstream tooling can enumerate the remaining work.