stdlib::to_toml behaves differently on dotted keys compared to TOML::Generator

Describe the Bug

TOML supports "dotted keys", that is about the same as our "dotted notation" when accessing facts.
Our stdlib::to_toml() uses toml-rb code, that has the issue when dealing with dotted keys.

I hit this when following the puppet-grafana's LDAP config example. It uses toml gem at the moment. When replaced with stdlib::to_toml() it produces a broken TOML.

As I see from unit tests, to_toml() expects a proper Puppet DSL Hash, while toml gem can work with dotted keys.

As a consequence, it's impossible to just replace TOML::Generator with our to_toml() function, because example syntax uses dotted key instead of a nested Hash or Array.

Another problem is sections reordering. E.g. [servers.attributes] section goes before [[servers]], which is wrong.

Expected Behavior

1. It'd be nice if dotted keys wouldn't be quoted.
2. It'd be nice if sections wouldn't be reordered.

Start with the stdlib::to_toml implementation and its unit tests, then compare its output with TOML::Generator for dotted keys and sections. Reproduce the puppet-grafana LDAP example and verify that dotted keys are not quoted and that sections retain the required ordering.