gcsemulator – `Objects.copy` JSON API Support

[commiterate]

gcsemulator@v1.0.0 currently doesn't support the Objects.copy API. It supports the related Objects.rewrite API instead.

gcsemulator logs:

2025-02-14 01:25:52 2025/02/14 06:25:52 POST request for bucket "files", object "files/testdir/testfile.bin/copyTo/b/files/o/files/testdir/destination_testfile.bin"
2025-02-14 01:25:52 2025/02/14 06:25:52 ERROR: responding with HTTP 400: unsupported POST request: /storage/v1/b/files/o/files%2Ftestdir%2Ftestfile.bin/copyTo/b/files/o/files%2Ftestdir%2Fdestination_testfile.bin?prettyPrint=false
2025-02-14 01:25:52 This may be a valid request, but we haven't implemented it in gcsemu yet.