Qt Network Authorization module improvements

A container Epic for improving qtnetworkauth module. Tentative high level prioritization below.

6.8

• [Needs new API] From new feature point of view, introducing convenience for using private URI schemes and https uri schemes is probably the most important.
  • QTBUG-124338
  • QTBUG-124339
  • QTBUG-124340
• [Needs new API] From security point of view, PCKE convenience should be introduced.
  • QTBUG-124327
• From existing code point of view, we should improve documentation
  • QTBUG-124323
  • QTBUG-124325
• From existing code point of view, we should address few high priority bugs (eg. double-encoding which prevents certain vendors)
  • QTBUG-81624
  • QTBUG-85265

6.9

This section has been moved to the QTBUG-130405

6.X

• • OpenID JWT Verification QTBUG-129383 (depends on research QTBUG-129378)

Possibly in future

• OpenID JWT Creation?
• QTBUG-124328 Investigate in-app browser tab usage