editor: Implement `From` instead of `Into` for converting `BlockId`s to `ElementId`s (#14839)

This PR replaces the `Into<ElementId> for BlockId` implementation with
`From<BlockId> for ElementId`.

This keeps in line with Rust's guidance for preferring implementing
`From`, and gives us more flexibility when converting.

Release Notes:

- N/A
a5b8094082Marshall Bowers committed on 7/19/2024, 8:24:12 PM· committed by GitHubparentd2efa12
1 file changedLine totals unavailable