Refactor GetObject Empty file Logic - Part 2

[waahm7]

Description of changes:

• Remove AWS_S3_AUTO_RANGE_GET_REQUEST_TYPE_INITIAL_MESSAGE request type and use AWS_S3_AUTO_RANGE_GET_REQUEST_TYPE_GET_OBJECT_WITH_PART_NUMBER_1 if AWS_S3_AUTO_RANGE_GET_REQUEST_TYPE_GET_OBJECT_WITH_RANGE fails due to an empty object. We will try downloading the first part again with partNumber; it will either download an empty file or download the updated file.
• Fix aws_s3_calculate_auto_ranged_get_num_parts for an empty file.
• Allow users to pass 0 as a size_hint.
• Fix onHeaders callback for an empty file.

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

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (2699a1f) 88.82% compared to head (cfc395b) 88.79%.

Additional details and impacted files

[](https://app.codecov.io/gh/awslabs/aws-c-s3/pull/396?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs) ```diff @@ Coverage Diff @@ ## skip-head2 #396 +/- ## ============================================== - Coverage 88.82% 88.79% -0.03% ============================================== Files 21 21 Lines 6085 6078 -7 ============================================== - Hits 5405 5397 -8 - Misses 680 681 +1 ``` | [Files](https://app.codecov.io/gh/awslabs/aws-c-s3/pull/396?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs) | Coverage Δ | | |---|---|---| | [source/s3\_auto\_ranged\_get.c](https://app.codecov.io/gh/awslabs/aws-c-s3/pull/396?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs#diff-c291cmNlL3MzX2F1dG9fcmFuZ2VkX2dldC5j) | `97.59% <100.00%> (-0.05%)` | :arrow_down: | | [source/s3\_util.c](https://app.codecov.io/gh/awslabs/aws-c-s3/pull/396?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs#diff-c291cmNlL3MzX3V0aWwuYw==) | `99.62% <100.00%> (ø)` | | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/awslabs/aws-c-s3/pull/396/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=awslabs)