Fix default range request callback report

[TingDaoK]

Issue #, if available:

typedef int(aws_s3_meta_request_receive_body_callback_fn)(

    /* The meta request that the callback is being issued for. */
    struct aws_s3_meta_request *meta_request,

    /* The body data for this chunk of the object. */
    const struct aws_byte_cursor *body,

    /* The byte index of the object that this refers to. For example, for an HTTP message that has a range header, the
       first chunk received will have a range_start that matches the range header's range-start.*/
    uint64_t range_start,

    /* User data specified by aws_s3_meta_request_options.*/
    void *user_data);

Description of changes:

• The range_start in the body callback is the byte index of the object that this refers to.
• It's confusing, but hey, the ship has sailed since first we add it. Not complain yet
• The auto range get respects this, but the default type get is not.
• Fixing the default type get to respect this.
• Add test so that with a range to get that write to a file will not mess up with file offset
• Add test to make sure the body callback respect the range correctly.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[sbSteveK]

AWS_ASSERT gets removed on non-debug builds. Any reason not to keep this and the below check in place for release builds and fail loudly?

[sbSteveK]

Curious about only debug fails. Otherwise looks good.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 88.23529% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.99%. Comparing base (2141dda) to head (ef8b9ec).

Files with missing lines	Patch %	Lines
source/s3_meta_request.c	84.61%	4 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           write-to-fd     #685      +/-   ##
===============================================
- Coverage        89.03%   88.99%   -0.04%     
===============================================
  Files               23       23              
  Lines             8591     8609      +18     
===============================================
+ Hits              7649     7662      +13     
- Misses             942      947       +5     

Files with missing lines	Coverage Δ
source/s3_auto_ranged_get.c	95.02% <100.00%> (+0.01%)	⬆️
source/s3_default_meta_request.c	94.24% <100.00%> (+0.21%)	⬆️
source/s3_meta_request.c	90.33% <84.61%> (-0.25%)	⬇️

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