chore: fix "react-in-jsx-scope" ESLint errors

This fixes all 50 violations of the [`react/react-in-jsx-scope`][0] lint
rule.

In the docs for that rule:

> If you are using the [new JSX transform from React 17][1], you should
> disable this rule by extending `react/jsx-runtime` in your eslint
> config (add `"plugin:react/jsx-runtime"` to `"extends"`).

We are, so we can do this! It also lets us remove many `React` imports.

[0]: https://github.com/jsx-eslint/eslint-plugin-react/blob/4467db503e38b9356517cf6926d11be544ccf4b1/docs/rules/react-in-jsx-scope.md
[1]: https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html

.eslintrc.js

@@ -1,6 +1,6 @@
 module.exports = {
   root: true,
-  extends: ['@react-native', 'prettier'],
+  extends: ['@react-native', 'plugin:react/jsx-runtime', 'prettier'],
   parser: '@typescript-eslint/parser',
   plugins: ['@typescript-eslint'],
   overrides: [