Implement streaming getcontent

[luke-lombardi]

Improves read speeds from this:

2024/12/17 21:09:34 Initial file len: 1048576000
2024/12/17 21:09:34 Response content len: 1048576000
2024/12/17 21:09:34 Hash of initial file: 0693cfe12235e1f11c34cb6e327c14b9b9d3ef23d66ad4e3bb128c4e376e1950
2024/12/17 21:09:34 Hash of stored content: 0693cfe12235e1f11c34cb6e327c14b9b9d3ef23d66ad4e3bb128c4e376e1950
2024/12/17 21:09:34 Hash of retrieved content: 0693cfe12235e1f11c34cb6e327c14b9b9d3ef23d66ad4e3bb128c4e376e1950
2024/12/17 21:09:34 Iteration 1: content length: 1048576000, file length: 1048576000, elapsed time: 2.228790 seconds
2024/12/17 21:09:37 Direct byte comparison found no differences.
2024/12/17 21:09:38 bytes.Equal confirms the slices are equal.
2024/12/17 21:09:38 Average MB/s rate of reading (GetContent): 448.674019

to this:

2024/12/17 21:27:32 Getting content stream for 0693cfe12235e1f11c34cb6e327c14b9b9d3ef23d66ad4e3bb128c4e376e1950
2024/12/17 21:27:35 Received EOF, ending stream
2024/12/17 21:27:35 Closing content channel
2024/12/17 21:27:35 Content channel closed, exiting loop
2024/12/17 21:27:35 Getting content stream for 0693cfe12235e1f11c34cb6e327c14b9b9d3ef23d66ad4e3bb128c4e376e1950
2024/12/17 21:27:37 Received EOF, ending stream
2024/12/17 21:27:37 Closing content channel
2024/12/17 21:27:37 Content channel closed, exiting loop
2024/12/17 21:27:37 Getting content stream for 0693cfe12235e1f11c34cb6e327c14b9b9d3ef23d66ad4e3bb128c4e376e1950
2024/12/17 21:27:39 Received EOF, ending stream
2024/12/17 21:27:39 Closing content channel
2024/12/17 21:27:39 Content channel closed, exiting loop
2024/12/17 21:27:39 Average MB/s rate of reading (GetContent): 1313.404790

This is only useful for sequential reads.