feat: support array format for unitToConvert option

[huhm]

No description provided.

[huhm]

Use Case

My Project has some code like this:

.font-14 {
  /* prettier-ignore */
  font-size: 14PX;
}

The plugin willl ignore the px convertor ,because 'px'!=='PX'. and then someday I have convert the PX too,but still let it avaliable to rolling-over，so I can't change the source. then there is a place for the unitToConvert: ["px","PX"]