feat(InputNumber): implement component (#2577)

Co-authored-by: Benjamin Canac <canacb1@gmail.com>

src/theme/index.ts

@@ -20,6 +20,7 @@ export { default as form } from './form'
 export { default as formField } from './form-field'
 export { default as input } from './input'
 export { default as inputMenu } from './input-menu'
+export { default as inputNumber } from './input-number'
 export { default as kbd } from './kbd'
 export { default as link } from './link'
 export { default as modal } from './modal'