etc: add -B, --bank to flux submission cli tab completion

Problem: The `-B, --bank` option is not supported in bash tab
completions.

Add this option to the supported bash tab completions for cli
submission commands.

Author: grondo

etc/completions/flux.pre

@@ -375,6 +375,7 @@ _flux_submit_commands()
 
     local COMMON_OPTIONS="\
         -q --queue= \
+        -B --bank= \
         -t --time-limit= \
         -o --setopt= \
         --setattr= \