fix: correct key order after add, flatten, keys, sort, reverse and shuffle

[antoinedeschenes]

Fixes issue #2387 where the wrong item is being deleted by del() after doing a add, flatten, sort, reverse or shuffle operation on a sequence.

What it does:

1. Always set the key on CandidateNode.AddChild
2. Ensure shuffle swaps the node keys when shuffling 2 items.
3. Ensure key is set on result arrays from keys operator
4. Adds tests validating the proper items are deleted.

Versions impacted: this issue started in v4.40.1

Comparison between yq 4.35.2, 4.45.4 and the proposed PR changes.

+ ./yq4.35.2 -n '.foo = ["lhs"] + ["rhs"] | del(.foo[1])'
foo:
  - lhs
+ ./yq4.45.4 -n '.foo = ["lhs"] + ["rhs"] | del(.foo[1])'
foo:
  - rhs
+ go run . -n '.foo = ["lhs"] + ["rhs"] | del(.foo[1])'
foo:
  - lhs
--------------------
+ ./yq4.35.2 -n '[3,2,1] | sort | del(.[2])'
- 1
- 2
+ ./yq4.45.4 -n '[3,2,1] | sort | del(.[2])'
- 2
- 3
+ go run . -n '[3,2,1] | sort | del(.[2])'
- 1
- 2
--------------------
+ ./yq4.35.2 -n '[3,[2],[[1]]] | flatten | del(.[2])'
- 3
- 2
+ ./yq4.45.4 -n '[3,[2],[[1]]] | flatten | del(.[2])'
- 2
- 1
+ go run . -n '[3,[2],[[1]]] | flatten | del(.[2])'
- 3
- 2
--------------------
+ ./yq4.35.2 -n '[3,2,1] | reverse | del(.[2])'
- 1
- 2
+ ./yq4.45.4 -n '[3,2,1] | reverse | del(.[2])'
- 2
- 3
+ go run . -n '[3,2,1] | reverse | del(.[2])'
- 1
- 2
--------------------
+ ./yq4.35.2 -n '{"a": 1, "b": 2, "c": 3} | keys | del(.[] | select(.=="b"))'
- a
- c
+ ./yq4.45.4 -n '{"a": 1, "b": 2, "c": 3} | keys | del(.[] | select(.=="b"))'
- a
- b
- c
+ go run . -n '{"a": 1, "b": 2, "c": 3} | keys | del(.[] | select(.=="b"))'
- a
- c
--------------------

[nvanheuverzwijn]

That fixes so much stuff

[mikefarah]

This looks really good 👍🏼 👍🏼 I'm about to go on an extended holiday - so reluctant to merge it an atm as I'll be away if anything happens. Will def review when I get back :)

[mikefarah]

Thinking more, I'll merge it in but won't release till I get back 👍🏼