Add support for the new option's snapshot fields

[OlegRa]

The options snapshot REST API endpoint now supports filtering and the resulting JSON contains new fields. The Go (see #279) and Python (see #446) SDKs already have a PRs with support for these new features. The required changes are:

• Extend the OptionChainRequest class with new (optional) filtering properties and initial client-side validation
• Add the new OptionSnapshotRequest class and use it for the ListSnapshotsAsync method (breaking change)
• Add the new IOptionSnapshot interface with Greeks and IV and use it instead of ISnapshot for options
• Add pagination support for the ListSnapshotAsync method into the extensions package

Optional task:

• Extract the common ISnapshotBase interface fromISnapshot and IOptionSnapshot interfaces.