…a from 3.38.0 to 3.39.0 in /packages/interactive_media_ads/android (#10950)

Bumps com.google.ads.interactivemedia.v3:interactivemedia from 3.38.0 to 3.39.0.

The latest update adds `@Nullable` to the SDK so the Kotlin static analysis is starting to fail where values are known nullable.

See https://developers.google.com/interactive-media-ads/docs/sdks/android/client-side/history

[![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=com.google.ads.interactivemedia.v3:interactivemedia&package-manager=gradle&previous-version=3.38.0&new-version=3.39.0)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`.

---

<details>
<summary>Dependabot commands and options</summary>
<br />

You can trigger Dependabot actions by commenting on this PR:
- `@dependabot rebase` will rebase this PR
- `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it
- `@dependabot merge` will merge this PR after your CI passes on it
- `@dependabot squash and merge` will squash and merge this PR after your CI passes on it
- `@dependabot cancel merge` will cancel a previously requested merge and block automerging
- `@dependabot reopen` will reopen this PR if it is closed
- `@dependabot close` will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
- `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency
- `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
- `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
- `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)

</details>

Fixes flutter/flutter#180048.

This PR adds error handling for `AVAssetWriter.startWriting` in `camera_avfoundation`. Previously, the boolean return value was ignored, which could mask initialization errors. Now, a `FlutterError` is returned if writing fails to start.

## Pre-Review Checklist

**Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.

This test file doesn't appear to ever have been part of a project, so was never run, and was testing a utility method that no longer exists.

This package was imported after I did a repository-wide sweep to convert all the non-plugin examples from Obj-C to Swift, to reduce use of a deprecated template.

This was done by:
- deleting the ios/ directory
- running `flutter create --platforms=ios .` using current `stable` (3.38.9)
- deleting the RunnerTest target and source, since we will never have native tests for this

## Pre-Review Checklist

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.