Incompatible option for yarn v2

**Description:**
`ionic start` command broken with Yarn v2 (aka berry).

**Steps to Reproduce:**
```bash
$ yarn set version berry
$ echo n | ionic start Test blank --type=angular
```
Or even:
```bash
$ yarn set version berry
$ echo n | yarn dlx -p @ionic/cli ionic start Test blank --type=angular
```

**Output:**
```
> yarn install --non-interactive
Unknown Syntax Error: Unsupported option name ("--non-interactive").

$ yarn install [--json] [--immutable] [--immutable-cache] [--check-cache] [--inline-builds]
[ERROR] An error occurred while running subprocess yarn.

yarn install --non-interactive exited with exit code 1.

Re-running this command with the --verbose flag may provide more
information.
```

**My `ionic info`:**
```
[WARN] You are not in an Ionic project directory. Project context may be missing.
Ionic:
Ionic CLI : 6.10.1
Utility:
cordova-res : not installed
native-run : not installed
System:
NodeJS : v14.5.0
npm : 6.14.5
OS : Linux 5.7
```

**Other Information:**
Migration guide: https://yarnpkg.com/advanced/migration

Start at the `ionic start` entry point and reproduce the failure with Yarn Berry using the commands and output in the issue. Trace where `yarn install --non-interactive` is invoked; done means `ionic start Test blank --type=angular` completes successfully with Yarn v2.

由索引模型根據 Issue 內容生成。