Number input testing

[tonybierman]

Summary of Changes

src/widget/number_input.rs

• Enhanced operate() method to expose text input and increment/decrement buttons
• Added unit tests

tests/number_input_integration_tests.rs (new file)

• Added integration tests using iced_test simulator

cargo test --lib number_input::tests && cargo test --test number_input_integration_tests

[genusistimelord]

lookin good!