New Feature: Input Source Indicator

[HollowMan6]

Now you can have input source indicator settings at Indicator tab, default is to show indicator everytime you type, move caret or switch input source. You can set to show indicator only when switching input source. You can also set popup animation and auto hide timeout.

[HollowMan6]

@yueduz 我注意到了你在 tuberry/ibus-tweaker#5 的issue，我觉得这种提示框形式比点提示的形式更直观，所以尝试制作了这个功能。你可以尝试一下我的插件v37版(GNOME 3.38)或者v38(GNOME 40)以上，欢迎提意见或者反馈！

操作指南：
https://github.com/HollowMan6/Customize-IBus/blob/main/GUIDE_CN.md#%E6%8C%87%E7%A4%BA

安装指南：

GNOME 扩展商店：https://extensions.gnome.org/extension/4112/customize-ibus/

目前v37版或者v38版可能还未通过审核上线GNOME 扩展商店，你可以稍作等待或者尝试其它安装方法：

https://github.com/HollowMan6/Customize-IBus#%E5%AE%89%E8%A3%85