We don't "uncapitalize" parts of an already-capitalized name when concatenating
words. In particular, we had UidRange in basic/uid-range.h and UGIDAllocationRange
in basic/uid-alloc-range.h, which is annoying.
This renames UidRange -> UidRangeEntry, and reintroduces UidRange which
contains the array of UidRangeEntry and its size.
No fucntional changes, just refactoring.
The array of uid range entries are already sorted. Hence, if x and y are
does not have intersection, then the remaining entries neither have
intersection with x.