Merge remote-tracking branch 'BeqJanus/ll-viewer-pull-requests/Beq-alpha-mask-on-emissive-fix' into DRTVWR-570-maint-Q

This is the most local fix for this issue, addressing the specific unqualified use of HAS_ALPHA_MASK.
If we find other issues with alpha mask being applied incorrectly then, it may be better to fix higher up in llvieweshadermgr.cpp by reverting the changes from SL-17532. 
For now, this way works for this specific bug without non-emissive side-effects.

following promotion of DRTVWR-575

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

Fix menu checks for enabling object sit and touch to not traverse the entire menu holder to update labels

Fix checks for empty LLSD maps to use size and not emptyMap which is for creating an empty LLSDMap type.

Merge remote-tracking branch 'RyeMutt/viewer/datapacker-crashfixes/datapacker-crashfixes' into DRTVWR-570-maint-Q

following promotion of DRTVWR-574

# Conflicts:
# indra/newview/llnetmap.cpp
# indra/newview/llnetmap.h

following promotion of DRTVWR-548