refacto: move filters and sorters in their own modules

Also exclude filters is taken into account in git ignore
fixes #892

lua/nvim-tree/utils.lua

@@ -113,76 +113,6 @@ function M.find_node(_nodes, _fn)
   return node, i
 end
 
----Create a shallow copy of a portion of a list.
----@param t table
----@param first integer First index, inclusive
----@param last integer Last index, inclusive
----@return table
-function M.tbl_slice(t, first, last)
-  local slice = {}
-  for i = first, last or #t, 1 do
-    table.insert(slice, t[i])
-  end
-
-  return slice
-end
-
-local function merge(t, first, mid, last, comparator)
-  local n1 = mid - first + 1
-  local n2 = last - mid
-  local ls = M.tbl_slice(t, first, mid)
-  local rs = M.tbl_slice(t, mid + 1, last)
-  local i = 1
-  local j = 1
-  local k = first
-
-  while (i <= n1 and j <= n2) do
-    if comparator(ls[i], rs[j]) then
-      t[k] = ls[i]
-      i = i + 1
-    else
-      t[k] = rs[j]
-      j = j + 1
-    end
-    k = k + 1
-  end
-
-  while i <= n1 do
-    t[k] = ls[i]
-    i = i + 1
-    k = k + 1
-  end
-
-  while j <= n2 do
-    t[k] = rs[j]
-    j = j + 1
-    k = k + 1
-  end
-end
-
-local function split_merge(t, first, last, comparator)
-  if (last - first) < 1 then return end
-
-  local mid = math.floor((first + last) / 2)
-
-  split_merge(t, first, mid, comparator)
-  split_merge(t, mid + 1, last, comparator)
-  merge(t, first, mid, last, comparator)
-end
-
----Perform a merge sort on a given list.
----@param t any[]
----@param comparator function|nil
-function M.merge_sort(t, comparator)
-  if not comparator then
-    comparator = function (left, right)
-      return left < right
-    end
-  end
-
-  split_merge(t, 1, #t, comparator)
-end
-
 ---Matching executable files in Windows.
 ---@param ext string
 ---@return boolean