[Yaml] fix parsing negative octal numbers

[xabbuh]

Q	A
Branch?	3.4
Bug fix?	yes
New feature?	no
Deprecations?	no
Tickets
License	MIT
Doc PR

[xabbuh]

while working on #34807 I realised that we actually do not correctly parse negative octal numbers

[stof]

Based on https://yaml.org/spec/1.2/spec.html#id2805071, I don't think negative octal actually make sense in YAML

[stof]

OK, according to https://yaml.org/type/int.html, they do make sense in YAML 1.1 (and this octal without 0o is the 1.1 octal syntax). I think we need to clarify which YAML spec we follow in the component (I think the current answer is "a mix of 1.1 and 1.2, being compliant with none of the 2 due to the mix")

[xabbuh]

In #34813 I am working on a deprecation. Looks like I need to improve that a bit so that in the future we will only support the 0o prefix.

[fabpot]

Thank you @xabbuh.