This commit adds support for resumable uploads to the internal HTTP
server used in GoogleCloudStorageBlobStoreRepositoryTests. This
way we can also test the behavior of the Google's client when the
service returns server errors in response to resumable upload requests.
The BlobStore implementation for GCS has the choice between 2
methods to upload a blob: resumable and multipart. In the current
implementation, the client executes a resumable upload if the blob
size is larger than LARGE_BLOB_THRESHOLD_BYTE_SIZE,
otherwise it executes a multipart upload. This commit makes this
logic overridable in tests, allowing to randomize the decision of
using one method or the other.
The commit add support for single request resumable uploads
and chunked resumable uploads (the blob is uploaded into multiple
2Mb chunks; each chunk being a resumable upload). For this last
case, this PR also adds a test testSnapshotWithLargeSegmentFiles
which makes it more probable that a chunked resumable upload is
executed.