[expo-dev-menu] fix ts and linting (#24497)

# Why

The `expo-dev-menu` package is set up a bit differently from the others
and includes code in the `./app` directory whereas the `lint` command
o

[expo-dev-menu] fix ts and linting (#24497)

# Why

The `expo-dev-menu` package is set up a bit differently from the others
and includes code in the `./app` directory whereas the `lint` command
only lints the `./src` directory.

A similar issue applies for the `tsc` command (the `app` directory was
not in the `tsconfig.json`).

# How

- updated the `lint` script to also lint the `./app` directory
- added a `ts:check` script
- added `./app` to `tsconfig.json`

# Test Plan

I loaded the dev menu in `bare-expo` locally to ensure no regressions
after the type changes.

# Checklist

- [ ] Documentation is up to date to reflect these changes (eg:
https://docs.expo.dev and README.md).
- [ ] Conforms with the [Documentation Writing Style
Guide](https://github.com/expo/expo/blob/main/guides/Expo%20Documentation%20Writing%20Style%20Guide.md)
- [ ] This diff will work correctly for `npx expo prebuild` & EAS Build
(eg: updated a module plugin).

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