Updates ion-rs to v0.14.0

[desaikd]

Description of changes: This PR works on updating ion-rs to v0.14.0 and adds related changes.

List of changes:

• Mostly includes name changes in ion-rs
  • Element -> IonElement
  • OwnedElement -> Element
  • SymbolToken -> IonSymbolToken
  • Struct -> IonStruct
  • Sequence -> IonSequence
  • OwnedStruct -> Struct
  • OwnedSequence -> Sequence