Uploads, copies or moves a file. If the file already exists then it is overwritten.

If x-source-path is set then the file is copied from an existing file and stored at path. If x-source-delete is set to 1, true or yes then the file is moved instead of copied. If x-source-path is not set then the content of the file must be uploaded by using form data (Content-Type = multipart/form-data). The new file is stored at path.

Note that there is special handling for files uploaded to uploads/providers/{providerId}/<<FileName>>.<<FileExtension>>. If this path is used, then the file will be associated with the provider with that identifier and also deleted when this provider gets deleted. Files must include a <<FileName>> and <<FileExtension>> to be associated with a provider.