Custom mime mapping

With 10.11.0 release, AzCopy allows to override the default and OS specific mime-mappings. Mime-mappings should be recorded in a json file in the below format, and will be preferred over OS specific mappings.

Set the following environment variable.
export AZCOPY_CONTENT_TYPE_MAP="/path/to/contentMap/file"

File format:

{
  "MIMETypeMapping": {
    ".323": "text/h323",
    ".aaf": "application/octet-stream",
    ".aca": "application/octet-stream",
    ".accdb": "application/msaccess",
  }
}