Include --select-tags items in the tags list for entities

[mheap]

When running deck with --select-tags, the tags are removed from the tags field on each entity to reduce duplication.

We've had multiple reports that this behaviour is confusing. Let's keep the values in tags in addition to populating select_tags

Acceptance Criteria

• The values provided by --select-tags (flag) or select_tags (config) are still present in the tags field for each entity
• Filtering continues to use the values in select_tags only