refactor(ui): recycle tag list in TagSearchPanel

[CyanVoxel]

Summary

This PR greatly improves the performance of the TagSearchPanel by recycling the TagWidgets in the scroll layout rather than constantly destroying and recreating them. There's also a few minor fixes in related areas:

Miscellaneous Changes and Fixes

• Use the "New Tag" title for both title and window of the "New Tag" modal
• Can now search library for tags from the Tag Manager and "Add Tag" preview panel modal
• The build tag panel spawned by the "Create & Add" button now correctly keeps focus on the tag name. This allows Esc to be used to quickly close the modal
• Order tag results by name before returning from SQL. This fixes a bug where only 100 "random" tags were returned before being sorted alphabetically on the UI side
• Only initialize TagDatabasePanel (Tag Manager) once instead of every time it's opened
• Only initialize FileExtensionModal (Tag Manager) once per-library instead of every time it's opened
• Remove redundant update calls to TagSearchPanel

[Tishj]

Ah the 100 explains a lot, I saw the __del__ I added trigger 100 times for every search!