feat: include submitter in email about submitted slides

[rjsparks]

fixes #6031

[codecov]

Codecov Report

Merging #6033 (e67770c) into main (09f3477) will decrease coverage by 0.04%.
The diff coverage is 90.82%.

@@            Coverage Diff             @@
##             main    #6033      +/-   ##
==========================================
- Coverage   88.67%   88.64%   -0.04%     
==========================================
  Files         288      290       +2     
  Lines       40001    40179     +178     
==========================================
+ Hits        35471    35616     +145     
- Misses       4530     4563      +33     

Impacted Files	Coverage Δ
ietf/doc/views_help.py	65.51% <ø> (ø)
ietf/doc/views_stats.py	74.80% <ø> (ø)
ietf/group/urls.py	100.00% <ø> (ø)
ietf/ietfauth/widgets.py	84.61% <ø> (ø)
ietf/submit/views.py	84.60% <ø> (ø)
ietf/group/views.py	90.25% <37.50%> (-0.29%)	⬇️
ietf/nomcom/views.py	92.90% <50.00%> (-0.22%)	⬇️
ietf/doc/views_doc.py	91.25% <76.00%> (-0.37%)	⬇️
ietf/doc/views_statement.py	94.96% <94.96%> (ø)
ietf/community/views.py	97.59% <100.00%> (ø)
... and 16 more

... and 3 files with indirect coverage changes