Create array shape for serialized action, serialized assertion

What's Changed

• Implement statement type as enum by @webignition in #282
• Implement EncapsulatingStatementData::containerType as enum by @webignition in #284
• Create array shape for serialized statement by @webignition in #286
• Create array shape for serialized action, serialized assertion by @webignition in #288

Full Changelog: 9.0...10.0