Add config key for QoL

[ahmubashshir]

Current behavior is <Tab>/<Shift><Tab> changes page and <Left>/<Right> changes suggestion.

I'd like to assign [/] for changing page and ,/. to change suggestion. I'd be happy if you implement this, or direct me to where this is handled, I'll try implementing myself.

Another suggestion is allowing users to merge 3 pages into one with a config key.

[GaZaTu]

@ahmubashshir you can try out #9

you just need to add the following snippet to ~/.config/gazatu.xyz/im-emoji-picker.ini

[customHotKeys]
1\sourceKeyChr=, 
1\targetKeySeq=Left
2\sourceKeyChr=.
2\targetKeySeq=Right
3\sourceKeyChr=[
3\targetKeySeq=Tab
4\sourceKeyChr=]
4\targetKeySeq=Shift+Tab
size=4