Add an option to skip checking duplicated files when adding existing file in `FastAppendAction`.

[liurenjie1024]

Is your feature request related to a problem or challenge?

See #960 (comment) Checking duplicated files in fast append action maybe time consuming, and we should allow user to skip it.

Describe the solution you'd like

No response

Willingness to contribute

• I can contribute to this feature independently
• I would be willing to contribute to this feature with guidance from the Iceberg Rust community
• I cannot contribute to this feature at this time