bwauth improvements (ex-parent ticket for SoP planned tasks)

Related issues:

• tpo/core/tor#25947 (closed)
• tpo/core/tor#26007 (closed)
• tpo/core/tor#26155 (closed)
• tpo/core/tor#26200 (closed)
• #26692 (closed)
• tpo/core/tor#26702 (closed)
• #26740 (closed)
• tpo/core/tor#26905 (closed)
• #28519 (closed)
• #28547 (closed)
• tpo/core/tor#28599 (closed)
• #28600 (closed)