Major VPTOOL usability improvements: VPTOOL version tracking, vplan dir handling, verif tags, PDF output

Created by: zchamski

This PR introduces a set of major improvements to VPTOOL usability:

• simplified configuration
  • no per-module vp_config.py file is needed anymore
• support for user-defined layout of per-module vplan databases
• new naming scheme for verification tags
  • names are now unique across a product
  • old-style tags are automatically migrated to the new naming scheme upon saving a database
• verification tags are now displayed in the Verification Item pane
  • displayed tags are read-only: they can be selected/copied, but cannot be modified
• the complete configuration of "most recently used" VPTOOL is tracked inside databases
• PDF output has been tested
• user documentation in VerifPlans was updated wrt. installation and configuration.

The databases of the FRONTEND module were re-saved and the corresponding markdown updated to demonstrate the corresponding differences.

See individual commits for the detail of the technical changes.