Fix a thread safety issue in the GL image worker.

LLViewerTexture::mNeedsCreateTexture needs to be an attomic bool since
it is written both in the main thread and in the GL image worker thread.

We can now enable threaded bump maps creation as a result of this fix.

I have read the CLA Document and I hereby sign the CLA

Various repo fixes

Add automatic PR labels

Add CLA bot

following promotion of DRTVWR-575

Fix SL-18511 TOS and MFA login failure handlers must cooperate to answer both reasons at the same time

following promotion of DRTVWR-574

following promotion of DRTVWR-548

Since the performance overhaul project, there should be essentially no difference between rigged meshes and non-rigged as far as vertex buffer management is concerned.

It might be safe to merge mSeedCapAttempts with mHttpResponderID, but for now leaving them separated, if only for making this mechanic clearer.

# Conflicts:
#	indra/newview/llmodelpreview.h

following promotion of DRTVWR-544

SL-18151 [SEC] MOAP can force multiple floaters open on users screen: The Viewer part of the fix for this JIRA - pulls in the updated Dullahan that exposes the user_gesture/is_redirect flags and uses them to determine what type of 'nav_type' is exchanged with viewer/plugin

Don't add popup to the list twice

Don't add popup to the list twice

Make notifications modal. When multiple ones are visible, first popup works, interacting with second one causes a crash. And it shouldn't be possible to change anything in floater when these notifications are visible