Use JSON / special serializer to format values

[felixfontein]

Use JSON serializing for choices values, same as for default and sample values.

Also use special serializer for INI value examples, and fix INI value example serialization in general. Thus now VALUE is used - as intended - when the option has no default (before it was None), and lists are no longer serialized as ['a', 'b', 'c'], but as a, b, c (['a', 'b', 'c'] is passed as a list whose first entry is ['a', whose second entry is 'b', and whose third entry is 'c'], which is NOT as intended).

Examples:

• https://docs.ansible.com/ansible/devel/collections/ansible/builtin/apt_module.html#parameter-purge vs. https://ansible.fontein.de/collections/ansible/builtin/apt_module.html#parameter-purge
• Defaults were already JSON: https://docs.ansible.com/ansible/devel/collections/ansible/builtin/apt_module.html#parameter-dpkg_options and https://ansible.fontein.de/collections/ansible/builtin/apt_module.html#parameter-dpkg_options
• https://docs.ansible.com/ansible/devel/collections/ansible/builtin/apt_key_module.html#parameter-state vs https://ansible.fontein.de/collections/ansible/builtin/apt_key_module.html#parameter-state
• https://docs.ansible.com/ansible/devel/collections/ansible/builtin/host_group_vars_vars.html#parameter-stage vs. https://ansible.fontein.de/collections/ansible/builtin/host_group_vars_vars.html#parameter-stage
• https://docs.ansible.com/ansible/devel/collections/ansible/builtin/host_group_vars_vars.html#parameter-_valid_extensions vs. https://ansible.fontein.de/collections/ansible/builtin/host_group_vars_vars.html#parameter-_valid_extensions

[tremble]

+1 I prefer the consistency

[samccann]

output LGTM... can't comment on the code :-)

[samccann]

Is this a requirement for 2.14 or just a 'nice to have' since we're past feature freeze date...

[felixfontein]

Is this a requirement for 2.14 or just a 'nice to have' since we're past feature freeze date...

It's not a requirement for 2.14, but it does fix wrong examples in documentation: the None instead of VALUE change is the more harmless of the two bugs fixed, the broken list in https://docs.ansible.com/ansible/devel/collections/ansible/builtin/host_group_vars_vars.html#parameter-_valid_extensions (correct: https://ansible.fontein.de/collections/ansible/builtin/host_group_vars_vars.html#parameter-_valid_extensions) is more serious.

[felixfontein]

@tremble @samccann thanks for reviewing this!