ZeroTrie follow-ups

[sffc]

The big ZeroTrie PR was merged as #2722

• Clarify what "bracket a window of strings" means in builder/mod.rs
• Should the get function be bounded on AsRef or Borrow? If Borrow, then get_str needs to be added
• Add DataBake impls and test whether they negatively impact compile times
• ZeroTrie types simplification #4408: Run performance benchmarks again to see if we can consolidate the flavors of ZeroTrie down to two or one

[sffc]

The first two bullet points are addressed in the PR.

I don't plan to pursue the third bullet point (use the const builder in DataBake) because we're already pushing the boundaries of baked data compile times and this change would only make it worse.

The fourth bullet point already has a separate tracking issue.