Align variable-length icons

[Bekaboo]

Description

First of all thanks for making such an awesome plugin! From time to time I find myself prefer using pure ASCII text instead of nerd icons, but using the first character of kind names (as suggested in README.md) is not informative, so I use the abbreviations of kind names instead for the symbol icons. However, the abbreviations are variable-length, which makes the variable names misaligned, as shown in the screenshot below.

Could we pad the symbol icons in the outline window so that symbols on the same level are always aligned?