feat(legacy view template): extract view to a separate file

[atlj]

Summary

Closes #370

Inspecting the codebase I've spotted that all of the view templates have the View initialized on a different file except the legacy view template. Having the view initialized in the index.tsx reduces the DX as anytime you make changes to the 'index.tsxfile, you will getInvariant Violation: Tried to register two views with the same name` error. This PR addresses these issues.

Test plan

1. Run create-react-native-library and select these options:

➜ ./create-react-native-library test ✔ What is the name of the npm package? … react-native-test ✔ What is the description for the package? … test ✔ What is the name of package author? … Burak Güner ✔ What is the email address for the package author? … md.burak.guner@gmail.com ✔ What is the URL for the package author? … https://github.com/atlj ✔ What is the URL for the repository? … https://github.com/atlj/react-native-test ✔ What type of library do you want to develop? › Native view ✔ Which languages do you want to use? › Kotlin & Swift 

2. Go inside src/
3. Make sure <Your Project Name>ViewNativeComponent.ts exists with proper code
4. Make sure the view is imported and exposed in index.tsx
5. Make sure the app is able to display the view
6. Make sure when you make changes to index.tsx, the Invariant Violation: Tried to register two views with the same name error doesn't appear.

[satya164]

Let's also do it for native modules and then merge

[satya164]

Let's name this file as <%- project.name -%>View.tsx to match the name of the component it exports

[satya164]

Generally good to avoid default exports

Suggested change

	export default UIManager.getViewManagerConfig(ComponentName) != null
	export const <%- project.name -%>View = UIManager.getViewManagerConfig(ComponentName) != null

[atlj]

You can find the diff here

[satya164]

Let's move the index file to common directory and change each type (legacy, new, mixed) to have this format for the view and module.

[satya164]

Burak said we don't need this anymore