fix: Improve Anywidget pagination and display for unknown row counts

[shuoweil]

Previously, when the total number of rows (row_count) was unknown (e.g., due to deferred computation or errors), it would incorrectly default to 0. This resulted in confusing UI, such as displaying "Page 1 of 0", and allowed users to navigate to empty pages without automatically returning to valid data.

current display strategy for the interactive table widget:

• When row_count is a positive number (e.g., 50):

  • Total Rows Display: Shows the exact count, like 50 total rows.
  • Pagination Display: Shows the page relative to the total rows, like Page 1 of 50.
  • Navigation: The "Next" button is disabled only on the final page.

• When row_count is None (unknown):

  • Total Rows Display: Shows Total rows unknown.
  • Pagination Display: Shows the page relative to an unknown total, like Page 1 of many.
  • Navigation: The "Next" button is always enabled, allowing you to page forward until the backend determines there is no more data.

Fixes #<428238610> 🦕

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[shuoweil]

@tswast Upon checking, the failed e2e tests are not related to my change.