0006-Always-Show-Placeholder-Option

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### Introduction

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Hello everyone. I have a feature request that I believe is not able to be achieved with the current `TextInput` component implementation.

### Details

Specifically, I would like it to be possible to always show the placeholder in a `TextInput`. This would be useful when there is a prompt for with a multiline input and the user can still follow along the prompt, typing, while the placeholder would dissapear as they type. I would leave it up to react developers to then make the `placeholder` content stateful for this type of behaviour, but it would at least need to be the case to expose such an `alwaysShowPlaceholder` prop.

### Discussion points

This would require the `boolean` prop `alwaysShowPlaceholder` to be exposed on the `TextInput` component. Then the question becomes if this type of behaviour is even possible according to native modules.

If this is possible already using the `TextInput` component, please let me know. But obviously I've read the docs and don't believe it is, thus this proposal :)