Navigation bar snippets

[wardlauren]

Adding the navigation rail, navigation bar, and tabs examples.

[snippet-bot]

Here is the summary of changes.

You are about to add 3 region tags.

• compose/snippets/src/main/java/com/example/compose/snippets/components/Navigation.kt:116, tag android_compose_components_navigationbarexample
• compose/snippets/src/main/java/com/example/compose/snippets/components/Navigation.kt:152, tag android_compose_components_navigationrailexample
• compose/snippets/src/main/java/com/example/compose/snippets/components/Navigation.kt:185, tag android_compose_components_navigationtabexample

---

This comment is generated by snippet-bot.
If you find problems with this result, please file an issue at:
https://github.com/googleapis/repo-automation-bots/issues.
To update this comment, add snippet-bot:force-run label or use the checkbox below:

• Refresh this comment