[2.0] Unify input component APIs

[stsrki]

We have

• TextEdit: with Text and TextChanged
• NumericEdit, NumericPicker: with Value, and ValueChanged
• DateEdit, DatePicker: with Date and DateChanged
• TimeEdit, TimePicker: with Time and TimeChanged
• Select: with SelectedValue and SelectedValueChanged
• etc.

We need to unify all APIs and make them more standardized. My proposal is to have

• Value, and ValueChanged for all input components.

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It will be better for the users as they will not need to remember each API for each component. A lot of times, they try <Text @bind-Value="@value" />, and it surprises them when it doesn't work.

The change will greatly improve our codebase also as we will not need to have many abstraction layers that convert the internal value into the external value via those APIs. We will also be able to centralize most of the validation logic at the BaseInputComponent.

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There are some edge-case components like Select that have several APIs, SelectedValue and SelectedValues for Multiple mode. I think naming them Value and Values is a good alternative.

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The change is obviously a breaking-change. So, we need to document all and update all examples in the documentation. Not to mention that a migration guide is much needed.

[richardschoen]

Not sure if it makes sense but you could leave current value settings and mark as deprecated but also add the new consistent ones. Depending on your user base size it would allow them to more slowly migrate to the new settings rather than breaking things.

[stsrki]

Not sure if it makes sense but you could leave current value settings and mark as deprecated but also add the new consistent ones. Depending on your user base size it would allow them to more slowly migrate to the new settings rather than breaking things.

That might be the good way for the time being. We can just propagate Value to internals without breaking anything. And as you said, users will have time to adjust.

[mrpmorris]

Definitely mark the existing ones [Obsolete], then remove them in the next major release.