Convert all the public API numeric fields to int

[addb]

Task description

Currently we have double, long for fields like playhead, length, timeToStart.
As per the XDM schema and the discussion with backend, those numeric fields should be updated to int

Affected APIs

• updatePlayhead
• all the createMediaObject APIs

DoD:

• Update the API signatures
• Refactor internal mapper to remove the conversion
• Update the respective tests
• Update migration-guide.md document

Additional implementation details or code snippet(s)

No response