input-pill: Add "onPillRemove" callback.
input-pill: Add "onPillRemove" callback.

This will now allow a callback to be triggered when a pill is
removed from the set.

eeshangarg/zulip,eeshangarg/zulip,eeshangarg/zulip,brainwane/zulip,zulip/zulip,rht/zulip,timabbott/zulip,shubhamdhama/zulip,hackerkid/zulip,synicalsyntax/zulip,showell/zulip,rishig/zulip,showell/zulip,tommyip/zulip,rht/zulip,hackerkid/zulip,shubhamdhama/zulip,shubhamdhama/zulip,punchagan/zulip,tommyip/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,timabbott/zulip,synicalsyntax/zulip,zulip/zulip,zulip/zulip,kou/zulip,jackrzhang/zulip,punchagan/zulip,dhcrzf/zulip,brainwane/zulip,rishig/zulip,andersk/zulip,jackrzhang/zulip,punchagan/zulip,kou/zulip,kou/zulip,rht/zulip,punchagan/zulip,brainwane/zulip,jackrzhang/zulip,jackrzhang/zulip,showell/zulip,punchagan/zulip,brainwane/zulip,punchagan/zulip,dhcrzf/zulip,hackerkid/zulip,jackrzhang/zulip,tommyip/zulip,kou/zulip,timabbott/zulip,showell/zulip,zulip/zulip,synicalsyntax/zulip,shubhamdhama/zulip,dhcrzf/zulip,brainwane/zulip,showell/zulip,andersk/zulip,rht/zulip,showell/zulip,eeshangarg/zulip,tommyip/zulip,kou/zulip,synicalsyntax/zulip,brainwane/zulip,rht/zulip,dhcrzf/zulip,rishig/zulip,rishig/zulip,hackerkid/zulip,andersk/zulip,tommyip/zulip,synicalsyntax/zulip,shubhamdhama/zulip,jackrzhang/zulip,timabbott/zulip,showell/zulip,andersk/zulip,hackerkid/zulip,shubhamdhama/zulip,punchagan/zulip,zulip/zulip,eeshangarg/zulip,rishig/zulip,tommyip/zulip,andersk/zulip,synicalsyntax/zulip,brainwane/zulip,timabbott/zulip,timabbott/zulip,hackerkid/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,rishig/zulip,rht/zulip,dhcrzf/zulip,andersk/zulip,kou/zulip,dhcrzf/zulip,rht/zulip,dhcrzf/zulip,zulip/zulip,shubhamdhama/zulip,synicalsyntax/zulip,timabbott/zulip,rishig/zulip,tommyip/zulip,jackrzhang/zulip