fix: registration with a prefix

[danielballan]

Back in July, deletion semantics were adjusted such that node.delete(...) deleted node itself (in addition to its contents). This requires a corresponding change to tiled register --prefix ... which should clear out the contents of the target node but not that node itself.

This was not caught at the time due to insufficient test coverage.

Checklist

• Add a Changelog entry
• Add the ticket number which this PR closes to the comment section

[genematx]

if the node that is being overwritten has internally-managed data, this will raise an error. I suppose it's the expected behavior, right?

[danielballan]

In addition to the test, here is an interactive run:

tiled register http://localhost:8000 --api-key secret --prefix x/y/z ~/files --verbose
  Overwriting '/x/y/z'
  Walking '/home/dallan/files'
    Resolved mimetype 'image/tiff' with adapter for '/home/dallan/files/a.tif'
    Resolved mimetype 'text/csv' with adapter for '/home/dallan/files/another_table.csv'
    Resolved mimetype 'image/tiff' with adapter for '/home/dallan/files/c.tif'
    Resolved mimetype 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' with adapter for '/home/dallan/files/tables.xlsx'
    Resolved mimetype 'image/tiff' with adapter for '/home/dallan/files/b.tif'
  Walking '/home/dallan/files/more'
    Grouped 3 tiff images into a sequence 'A'
    Grouped 2 tiff images into a sequence 'B'
  Walking '/home/dallan/files/more/even_more'
    Resolved mimetype 'image/tiff' with adapter for '/home/dallan/files/more/even_more/f.tif'
    Resolved mimetype 'image/tiff' with adapter for '/home/dallan/files/more/even_more/e.tif'