Improve the Study by card state or tag dialog

The Study by card state or tag dialog

• Add a title "Study by card state or tag".
• Remove "Select x cards from the deck".
• Add "Number of cards" to the border of the text field (see reference).
• Add a unit "card"/"cards" to the box.
• Change the text selection like in https://github.com/ankidroid/Anki-Android/pull/20551.
• Replace "Select" with "Create".
• If the resulting filtered deck is empty (i.e., no cards match the criteria), a red warning should appear and the button should be disabled, instead of an error dialog (see reference).
  • Also, make sure this bug is fixed: when there are no cards matching some selections like "Due cards only", a filtered deck with of new cards is created.
• Show a warning when the input is invalid, limit the digits, and prevent leading zeros, like in https://github.com/ankidroid/Anki-Android/pull/20520, except without input steppers.

Reference dialogs