input-number: Should trigger ngModelChange when typing

What problem does this feature solve?

We should always trigger ngModelChange when typing. If developers want to update model value only on blur, they can easily use ngModelOptions to specify its behavior.

我觉得我们应该在用户输入时始终触发 ngModelChange 事件。如果开发者希望在 blur 时才触发更新，可以简单的通过设置 ngModelOptions 指定。

But now we hardcoded its behavior, developers cannot change its behavior back. We use input-number to input integers for most situations, (input) events work fine for those cases.

但是现在在代码中强制了这种行为，用户却无法改回默认的 input 触发。input-number 大多数还是用于输入整数的情况；input 事件对于这种情况工作良好。

Now the behavior is very strange for nonempty validation. The submit button keeps disabled state after user typed some number.

现在做表单的非空验证时行为很奇怪。用户输入了值，提交按钮还是禁用不能点击的状态。

Ref: https://github.com/NG-ZORRO/ng-zorro-antd/issues/2708

What does the proposed API look like?

Trigger ngModelChange event when users’ typing

[vthinkxie]

Hi all, this issue will be fixed after ng-zorro-antd v9 released

[joaomvfsantos]

Please consider this. We should not lock out developers to use a functionality because of a possible problem on float since it works correctly on integer. Furthermore, developers could use ngModelOptions to use this behaviour whenever they need to.