Paving the way to remove `ExcerptId`. Done in this PR:
- Unshipped the stack trace view
- Get rid of `push_excerpts`
- Get rid of some callers of `remove_excerpts`
We still need to remove some calls to `remove_excerpts` and other APIs,
especially in `randomly_edit_excerpts` and collaboration.
Release Notes:
- The stack trace multibuffer view has been removed.
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Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>