a very dirty fix for unchanged File Colors

(cherry picked from commit 69c0175b3e76cbccc6237bddedb9f8f07eee1bee)
use JBColor functions to avoid colors caching
avoid double wrapping to JBColor
(r=Anton.Makeev) avoid O(N) reallocations (and O(N^2) memory transfer) where N is number of changes due to usage of copy on write list: latter isn't needed as all accesses to list are synchronized. Its usage was replaced with ArrayList com.intellij.history.core.changes.ChangeSet$3.run: 6,772,591,320 (19.93%) bytes in 66,975 (0.01%) objects (avg size 101,121 bytes) java.lang.Object[]: 6,772,591,320 (19.93%) bytes in 66,975 (0.01%) objects (avg size 101,121 bytes)