Closes #4161: Make MediaState extension methods visible for consuming apps.

[pocmo]

---

Pull Request checklist

• Quality: This PR builds and passes detekt/ktlint checks (A pre-push hook is recommended)
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry or does not need one
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features

After merge

• Milestone: Make sure issues closed by this pull request are added to the milestone of the version currently in development.
• Breaking Changes: If this is a breaking change, please push a draft PR on Reference Browser to address the breaking issues.

[sblatz]

This all looks great to me 😄

I did add one more helper function in Fenix that we should consider adding here:

/* Helper function to invert a MediaState */
fun MediaState.inverse(): MediaState {
    return when (this) {
        is MediaState.Playing -> {
            MediaState.Paused(
                session = session,
                media = media
            )
        }
        is MediaState.Paused -> {
            MediaState.Playing(
                session = session,
                media = media
            )
        }
        is MediaState.None -> { MediaState.None }
    }
}

[pocmo]

@sblatz 👀 I wonder what you need that for. I'd expect those to only come out of MediaStateMachine.

[jonalmeida]

bors r=csadilek

[bors]

Build succeeded

• Taskcluster (push)