SE-0558: Bulk update operations for `MutableSpan` and `MutableRawSpan`

Hi everyone. The review of SE-0558, Bulk update operations for MutableSpan and MutableRawSpan, begins now and runs through October 28, 2026. Reviews are an important part of the Swift evolution process. All review feedback should be either on this forum thread or, if you would like to keep your feedback private, directly to the review manager via the forum messaging feature. When contacting the review manager directly, please keep the proposal link at the top of the message. What goes into a r...