Jparcill/5547 Stream Distributions CSV instead of pregenerating

[jparcill]

Resolves #5477

Description

Stream the exporting of the Distributions CSV instead of generating the CSV before download. This allows download to start immediately and at this point the download can occur as long as the client wants.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Changed the rspec to handle streams

Another test that I did was to simulate a large download with the following code on my local env.

1000.times do
  distributions.each do |distribution|
    yield CSV.generate_line(build_row_data(distribution))
  end
end

This downloaded a 3.5 MB file over >30 seconds.

[jparcill]

I'm not sure this is actually accurate. I originally used find_each when trying to export on my localenvironment and the code worked.

indicating that the distributions were not in memory yet

I've since switched to using each instead just so that the spec file runs since the tests expect an array