Batch file operations

Accepts NDJSON (newline-delimited JSON) where each line is an addFile, copyFile, or deleteFile instruction. All add/copy operations must come before all delete operations.

JSON-lines payload:

	'{"type":"addFile","path":"...","xetHash":"...","mtime":...,"mtimeNanos":...,"contentType":"..."}' +
	'{"type":"copyFile","path":"...","xetHash":"...","sourceRepoType":"...","sourceRepoId":"...","mtime":...,"mtimeNanos":...,"contentType":"..."}' +
	'{"type":"deleteFile","path":"..."}'