fix(workspace): take a path as disk spells it on a disk that folds names

changelog.d/workspace-path-disk-spelling.fixed.md

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+- On a disk that folds names, as macOS's does by default (case, and Unicode normalization), the workspace's tools take a path as disk spells it. A `path` spelled otherwise, such as `work/SRC` for disk's `src/`, reaches disk's files, and `glob`, `grep` and `ls` used to name what they found from that spelling. So the workspace took each file in a second time under that name, announced it as created, and announced it deleted at the next pass over the mount; a `write` there was held under the name given while disk put it in `src/`. Now each segment of a `path` that reaches an entry under another spelling takes the entry's own name, from the mount's root down, and answers name files as disk lists them: `read work/SRC/a.ts` answers with `path: "work/src/a.ts"`. A segment disk doesn't have keeps the spelling given, and nothing past a symlink, or past a `..` that climbs above the mount's root, is respelled. `readBinary`, `readBinaryFromDisk`, `readFileFromDisk` and `writeBinary` take their paths the same way; `resolveAbsolutePath` takes its path as given, and the path it returns reaches the same file. A nested mount's directory is now known in its configured spelling and in disk's: `read`, `read_image`, `write`, `edit` and `delete`, and the public readers and writer, refuse a path into it spelled in another case or normalization form as that mount's, and an outer mount no longer takes in the files of a nested mount whose directory was configured in another spelling than disk's. On a disk that tells spellings apart, every answer is as before.