Allow ignoring a resolved configuration

## Feature Request

AVA should support a way to ignore a resolved configuration, for example a (mono-)repo's `ava.config.js`.

Possible solutions:

- Have configurations in a directory take precedence over a parent configuration (e.g. `"ava"` field in a `package.json` and a root `ava.config.json`)
- Add a `root: boolean` option to configs that specifies not to search for parent configurations
- Add a CLI flag to ignore parent configurations (e.g. `npx ava --ignore-parent-configs`)
- If the resolved configuration contains the current test in its `"ignores"`, skip it

## Rationale

I'm trying to update the examples to AVA 6 (#2993), but they resolve the repo's [`ava.config.js`](https://github.com/avajs/ava/blob/main/ava.config.js) when trying to run them:

```
…/examples/endpoint-testing
$ npx ava
⚠ Using configuration from …/ava.config.js

✘ Couldn’t find any files to test

$ npx ava test.js
⚠ Using configuration from …/ava.config.js

✔ get /user
─

1 tests passed
```

The TypeScript examples have a custom config:

```jsonc
// package.json
"ava": {
"typescript": {
"compile": "tsc",
"rewritePaths": {
"source/": "build/"
}
}
}
```

This results in the tests failing due to conflicting configs:

```
…/examples/typescript-basic
$ npx ava

✘ Conflicting configuration in ../../ava.config.js and package.json
```

Attempting to ignore the examples in `ava.config.js` doesn't work:

```diff
- files: ['test/**', '!test/**/{fixtures,helpers}/**', ...skipWatchMode],
+ files: ['test/**', '!test/**/{fixtures,helpers}/**', '!examples', ...skipWatchMode],
```

Start by reproducing the configuration resolution from the examples/endpoint-testing and examples/typescript-basic directories with `npx ava`; inspect the repository's `ava.config.js` and each example's `package.json`. The work is complete when examples can use their intended configuration without the repository configuration causing missing tests or conflicts.

Written by the indexing model from the issue text.