Fixed on reading un-encoded copy-source header field

[majdyz]

Copy-source property can be stored un-encoded in the blob storage. We need to encode the property while reading it so that getBlobAttributes is not throwing an exception in such a case.

To reproduce the bug:

• Create a file in the blob storage with a space in the filename.
• Copy the file to another target using the COPY Blob API (https://docs.microsoft.com/en-us/rest/api/storageservices/copy-blob, make sure to not escape the x-ms-copy-source header while sending the request). Here is the sample of HTTP PUT request to do the copy:

  PUT /path/to/your_copied_file HTTP/1.1
  Host: YOUR_STORAGE_ACCOUNT.blob.core.windows.net
  Authorization: Bearer YOUR_BEARER_TOKEN
  x-ms-version: 2020-08-04
  x-ms-copy-source-authorization: Bearer YOUR_BEARER_TOKEN
  x-ms-copy-source: https://YOUR_STORAGE_ACCOUNT.blob.core.windows.net/path/to/your sample file with space

• Try to execute CloudBlob.downloadAttributes on the copied file.