emoji_picker: Further improve emoji picker navigation.
emoji_picker: Further improve emoji picker navigation.

This further improves the emoji picker by introducing two new behaviors:

1: If the cursor is at the end of the input box then pressing `right_arrow`
moves the focus down into `emoji_catalog.

2: If the currently focused emoji is the first emoji in the `emoji_catalog`
then pressing `left_arrow` moves focus back to search filter.

punchagan/zulip,eeshangarg/zulip,brainwane/zulip,amanharitsh123/zulip,Galexrt/zulip,punchagan/zulip,punchagan/zulip,dhcrzf/zulip,rishig/zulip,brockwhittaker/zulip,rht/zulip,tommyip/zulip,brockwhittaker/zulip,punchagan/zulip,tommyip/zulip,hackerkid/zulip,zulip/zulip,hackerkid/zulip,rishig/zulip,brockwhittaker/zulip,punchagan/zulip,showell/zulip,zulip/zulip,brockwhittaker/zulip,punchagan/zulip,rishig/zulip,Galexrt/zulip,showell/zulip,Galexrt/zulip,andersk/zulip,shubhamdhama/zulip,rht/zulip,dhcrzf/zulip,rishig/zulip,kou/zulip,timabbott/zulip,shubhamdhama/zulip,eeshangarg/zulip,rht/zulip,amanharitsh123/zulip,brainwane/zulip,rht/zulip,dhcrzf/zulip,Galexrt/zulip,showell/zulip,verma-varsha/zulip,rishig/zulip,Galexrt/zulip,timabbott/zulip,tommyip/zulip,timabbott/zulip,jackrzhang/zulip,verma-varsha/zulip,amanharitsh123/zulip,jackrzhang/zulip,jackrzhang/zulip,verma-varsha/zulip,Galexrt/zulip,mahim97/zulip,hackerkid/zulip,punchagan/zulip,timabbott/zulip,jackrzhang/zulip,synicalsyntax/zulip,mahim97/zulip,hackerkid/zulip,eeshangarg/zulip,synicalsyntax/zulip,andersk/zulip,dhcrzf/zulip,zulip/zulip,shubhamdhama/zulip,tommyip/zulip,jackrzhang/zulip,tommyip/zulip,timabbott/zulip,verma-varsha/zulip,shubhamdhama/zulip,showell/zulip,andersk/zulip,synicalsyntax/zulip,tommyip/zulip,zulip/zulip,amanharitsh123/zulip,eeshangarg/zulip,hackerkid/zulip,andersk/zulip,mahim97/zulip,amanharitsh123/zulip,showell/zulip,andersk/zulip,zulip/zulip,brainwane/zulip,andersk/zulip,synicalsyntax/zulip,timabbott/zulip,eeshangarg/zulip,Galexrt/zulip,rht/zulip,synicalsyntax/zulip,rht/zulip,kou/zulip,shubhamdhama/zulip,jackrzhang/zulip,kou/zulip,kou/zulip,andersk/zulip,jackrzhang/zulip,dhcrzf/zulip,rishig/zulip,hackerkid/zulip,zulip/zulip,mahim97/zulip,shubhamdhama/zulip,eeshangarg/zulip,verma-varsha/zulip,zulip/zulip,brockwhittaker/zulip,mahim97/zulip,brainwane/zulip,showell/zulip,kou/zulip,verma-varsha/zulip,brainwane/zulip,hackerkid/zulip,timabbott/zulip,eeshangarg/zulip,synicalsyntax/zulip,rishig/zulip,mahim97/zulip,tommyip/zulip,brockwhittaker/zulip,synicalsyntax/zulip,kou/zulip,shubhamdhama/zulip,brainwane/zulip,showell/zulip,rht/zulip,amanharitsh123/zulip,dhcrzf/zulip,brainwane/zulip,dhcrzf/zulip,kou/zulip