Permit updating the value of code inputs

[pachun]

Prior to this commit, there is no way to programmatically update the value of a CodeInput.

After this commit, sending a value prop to the CodeInput component allows us to control the value displayed in the CodeInput, by changing the content of the variable that's set as the CodeInput's value prop.

Overview

I wanted to be able to change the value displayed by a CodeInput component. Using TextInput's value prop didn't work because there's local state in the CodeInput component that controls the value that's displayed.

Test Plan

I verified that my changes work by forking your repo, creating a branch (permit-code-input-value-changes - which is the fork I'd suggesting we merge in this PR) and committing my changes to that branch. Rather than publish the fork to NPM, I created another branch (on top of the previous one), on which I ran npm run build, removed /lib from the .gitignore, and pushed back up to my repo. I think we don't want the /lib checked in here, so I excluded it from this PR, but the only way I knew to test my changes without publishing to NPM was to include lib in a branch and then add my fork as a dependency to the project I'm working on by running yarn add pachun/react-native-dialog#include-lib. Once the fork was added as a dependency of the project I'm working on, I was able to control the value displayed by CodeInput components by doing:

  const [confirmationCode, setConfirmationCode] = React.useState("")

// ...

<Dialog.CodeInput
  autoFocus
  value={confirmationCode}
  onChangeText={setConfirmationCode}
  testID="Confirmation Code Input"
/>

Now, anywhere where I call setConfirmationCode(__value__), will update the value displayed by the CodeInput component to __value__, which I couldn't find a way to do prior to making the changes in this fork.

Other notes about the change:

I really dislike useEffects. I added one in this PR because it was the easiest way to get the behavior that I needed and get back to working on my project. I'm definitely open to implementing this any other way, possibly conforming to a project convention that I missed somewhere.

EDIT:

Since this has been in review for a bit: For anyone else wanting this feature now, you can also do yarn add pachun/react-native-dialog#include-lib or the NPM equivalent npm install pachun/react-native-dialog#include-lib --save to install of version of react-native-dialog that'll let you control the value of a CodeInput component.