GetArchive: replace path with subdirectory+include

This MR:

• Deprecates bytes path = 5
• Adds bytes subdirectory = 7
• Adds repeated bytes include = 8

With the addition of subdirectory, path is deprecated in favor of include. include and exclude are relative to subdirectory. subdirectory is passed to git archive in such a way that it is not included in archive entry filenames, eliminating the need for elide_path.

Existing calls using path are rewritten to include = [path], which will have the same behavior. Using subdirectory = '...' instead of path = '...' will have the effect of eliding the subdirectory from archive entry filenames, as in !2342 (merged).

This is an alternative to !2342 (merged) and !2363 (closed), along the lines of previous discussion about subdirectory/root_dir:

• !2342 (comment 374040704)
• !2342 (comment 374661594)
• !2342 (comment 375483730)
• !2363 (comment 378846774)