add does not modify pendingWires

John Billingsley reported a [problem with sweep]( https://groups.google.com/g/cadquery/c/UrPx8CiSdY0/m/rYtuHCR6AgAJ).

While looking into John's Billingsley problem and learning how to use sweep
I ran into a problem that I feel is a bug.

When I create two separate sketches, then put them both on the stack using
`add()` and then do a sweep(). The result is a shape that was created only
using the rectangle in s1. See the shape on the left in the screenshot below
and lines 1..22 in the code below and in [this repo](https://github.com/winksaville/cq-pendingWires-bug):
```
(cq-dev) wink@3900x:~/prgs/CadQuery/projects/pendingWires-bug
$ cat -n pendingWires-bug.py
1 import cadquery as cq
2
3 # The path that we'll sweep
4 path = cq.Workplane("XZ") .moveTo(0, 4) .radiusArc(endPoint=(4, 0), radius=4)
5 #show_object(path)
6
7 # Sketch 1
8 s1 = cq.Workplane("YZ").moveTo(0, 4).rect(2, 1)
9 #show_object(s1)
10
11 # Sketch 2
12 s2 = cq.Workplane("XY").moveTo(4, 0).circle(0.5)
13 #show_object(s2)
14
15 # BUG?: len(c.ctx.pendingWires) should equal 2 at this point, but it equals 1
16 c = s1.add(s2)
17 log(f"len(c.ctx.pendingWires)={len(c.ctx.pendingWires)}")
18 #show_object(c)
19
20 # This not the desired output, only the rectangle in s1 was used in the sweep
21 result = c.sweep(path, multisection=True)
22 show_object(result.translate((0, 0, 0)))
23
24 # Clearing pending wires and looking at each sets pendingWires
25 c.ctx.pendingWires = []
26 r = c.each(lambda shape: shape)
27 log(f"len(r.ctx.pendingWires)={len(r.ctx.pendingWires)}")
28
29 # This is the desired result, sweep from rectangle to circle
30 result = r.sweep(path, multisection=True)
31 show_object(result.translate((0, 5, 0)))```
```
A work around, lines 24..31 above, is to use
[each()](https://github.com/CadQuery/cadquery/blob/cc1f8f3183a16a1d222959c5860280e7bd3259bb/cadquery/cq.py#L2077)
to look at all of the items on the stack. What `each()` does is if an item
is a `Wire` and not `forConstruction`
[it calls](https://github.com/CadQuery/cadquery/blob/cc1f8f3183a16a1d222959c5860280e7bd3259bb/cadquery/cq.py#L2121)
the method [_addPendingWire()](https://github.com/CadQuery/cadquery/blob/cc1f8f3183a16a1d222959c5860280e7bd3259bb/cadquery/cq.py#L1982).
Which appends the `Wire` to ctx.pendingWires. The result is that the desired shape is created.
See the shape on the right in the screenshot below:


Bắt đầu trong cadquery/cq.py với add(), ctx.pendingWires, each() và _addPendingWire(), sử dụng bản tái hiện pendingWires-bug.py của issue. Kiểm tra vì sao add() chỉ để lại một wire đang chờ; hoàn tất khi cả hai sketch vẫn khả dụng cho sweep và bản tái hiện tạo ra kết quả từ hình chữ nhật sang hình tròn mà không cần workaround each().

Do mô hình lập chỉ mục viết ra từ nội dung của issue.