Add support for EAS CLI installs

### Topic and scope of discussion
Improved support for EAS CLI. It's not super important, bc you can just use `npx eas-cli`, but still might be useful to include in the github action.

### Big changes
- Make Expo CLI optional to install
- Add optional EAS CLI install
- Make sure caching works with both Expo and EAS CLI
- Unify credential inputs for both Expo and EAS

### Proposed inputs

old | new | why
--- | --- | ---
`expo-packager` | `packager` | Users probably pick either npm or yarn, not a different one for both.
`expo-patch-watchers` | `patch-watchers` | This applies to the system, so both or none.
`expo-username` | `username` | Unify this for both Expo and EAS CLI.
`expo-password` | `password` | Unify this for both Expo and EAS CLI.
`expo-token` | `token` | Unify this for both Expo and EAS CLI.
\- | `eas-version` | New, for EAS CLI
\- | `eas-cache` | New, for EAS CLI
\- | `eas-cache-key` | New, for EAS CLI
`expo-version` | `expo-version` | _not changed_
`expo-cache` | `expo-cache` | _not changed_
`expo-cache-key` | `expo-cache-key` | _not changed_

### Other changes

input | what
--- | ---
`expo-version` | Defaults to `null`, skipping installation when not defined
`eas-version` | Defaults to `null`, skipping installation when not defined

### Gotcha's

1. We can't really authenticate if neither Expo nor EAS CLI is installed. We have to add warnings/debugging for that when this happens.