config: expand config:info()

Closes #9780

@TarantoolBot document
Title: Expansion of `config:info()`

Before this patch, the `meta` field of the `config:info()` function
contained the meta data of the last load, even if it was unsuccessful
reload. This can be inconvenient because if the reload fails, we expect
that the last configuration that was successfully applied is used, but
its metadata was lost.

Now `config:info()` can take one argument — the version of the
information that should be returned by the function. If no arguments are
specified or the argument is the string `v1`, the return value has the
same structure as before. If the argument is the string `v2`, the `meta`
field in the return value has fields - `active` (meta for the last
successfully applied configuration) and `last` (meta of the last loaded
configuration). Currently only these values are accepted.