fix: use ReactElement | null for Text and AnimatedText return type (fixes #4871)

[krishnamanieee]

Motivation

After upgrading to react-native-paper v5.15.0, consumers see TypeScript errors when using Text (and when using styled(Text)):

1. Text as JSX: 'Text' cannot be used as a JSX component. Its return type 'ReactNode' is not a valid JSX element.
2. styled(Text): Argument of type 'TextComponent<never>' is not assignable to parameter of type 'NativeTarget' | 'WebTarget'.

This happens because the exported component types declared a return type of ReactNode. In current React/TypeScript, a component used as JSX must return React.ReactElement | null. This change updates the TextComponent and customAnimatedText typings to return React.ReactElement | null so that Text and AnimatedText are valid JSX components and compatible with styled().

Related issue

Fixes #4871

Test plan

• TypeScript: Run yarn typescript in the repo root (and in a consumer app using Text and optionally styled(Text)) and confirm no type errors.
• Lint/tests: Run yarn lint and yarn test to ensure nothing else is broken.
• Usage: Use <Text>, <AnimatedText>, and styled(Text) in a TypeScript project; tsc --noEmit (or bun run tsc:check) should pass.

[callstack-bot]

Hey @krishnamanieee, thank you for your pull request 🤗. The documentation from this branch can be viewed here.