Serialize more types with ToString

Since we use Newtonsoft.JSON with the default settings to serialize test or step parameters, some values are serialized in a less-than-optimal way:

- Enums are serialized as their underlying values instead of strings (see https://github.com/orgs/allure-framework/discussions/2560)
- Types from System.Reflection (PropertyInfo, etc) blows up
- Something else?...

Those are obvious cases when ToString would be preferrable.

Start by locating where test or step parameters are serialized with Newtonsoft.Json's default settings. Reproduce the enum and System.Reflection cases described in the issue, then identify the intended set of values for ToString-based serialization; done means those cases serialize without errors and with readable strings.

Written by the indexing model from the issue text.