[Submission list] Show graphic and message when an LOI has no submissions

[gino-m]

Material icon: inbox_24px
Icon: 36x36 "ground/sys/light/outline": #727970
Circle: 86x86 "ground/sys/light/surface-container-high": #E8E9E3

@rfontanarosa @amysorto @vittorino FYI

[rfontanarosa]

already done.