Fix readFile on Windows

[niyatim23]

Issue #, if available:

What was changed?

• Fix readFile to work properly for multiline files on Windows

Why was it changed?

• The readFile was not working as expected from WebRTC C SDK in ASCII mode. To ensure that fread, fseek and ftell works on Windows as expected, compatible functions with expected return values are evaluated and used.

How was it changed?

• Use Windows-specific _fseeki64 and _ftelli64 as the traditional fseek and ftell are non-compliant on systems that do not provide the same guarantees as POSIX. On these systems, setting the file position indicator to the end of the file using fseek() is not guaranteed to work for a binary stream, and consequently, the amount of memory allocated may be incorrect, leading to a potential vulnerability ([Reference](https://wiki.sei.cmu.edu/confluence/display/c/FIO19-C.+Do+not+use+fseek()+and+ftell()+to+compute+the+size+of+a+regular+file))
• fread would either return 1, i.e, the number of objects we've requested it to read or it would run into end-of-file / error. fread does not distinguish between end-of-file and error, so I used feof to determine it is indeed end-of-file and not an error. (Reference)

What testing was done for the changes?

• Wrote unit and functionality tests

• Tested manually on Windows

• Tested manually on MacOS

  

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 80.41%. Comparing base (ffef12d) to head (97c2548). Report is 1 commits behind head on develop.

:exclamation: Current head 97c2548 differs from pull request most recent head 6b63034. Consider uploading reports for the commit 6b63034 to get more accurate results

Files	Patch %	Lines
src/utils/src/FileIo.c	40.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #249 +/- ## =========================================== + Coverage 80.34% 80.41% +0.06% =========================================== Files 53 53 Lines 10808 10810 +2 =========================================== + Hits 8684 8693 +9 + Misses 2124 2117 -7 ```

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[hassanctech]

Nice! Let's add some unit test coverage here for this bug fix, one that fails before the change but succeeds now.

[disa6302]

Awesome! In addition to unit test, are there unit tests in WebRTC we should remove from the gtest filter to test file related operations (I think the file caching tests in there are disabled at the moment for windows) ? If so, can we open a PR in webrtc referencing this commit, enabling the file cache specific tests to make sure it is all good?

[niyatim23]

Awesome! In addition to unit test, are there unit tests in WebRTC we should remove from the gtest filter to test file related operations (I think the file caching tests in there are disabled at the moment for windows) ? If so, can we open a PR in webrtc referencing this commit, enabling the file cache specific tests to make sure it is all good?

Enabled Signaling tests on Windows in: https://github.com/awslabs/amazon-kinesis-video-streams-webrtc-sdk-c/pull/1933