[Fix] Duplicate existed function util and missing export

[husainazkas]

There are 3 duplicates firstWhereOrNull extension util, so I decide to remove the duplicates and move to the correct location in lib\get_utils\src\extensions\iterable_extensions.dart to prevent from confusing and inconsistency possibility in future.

Also I added export for lib\get_connect\http\src\request\request.dart inside lib\get_connect\connect.dart for consistency of exports necessary module just like the lib\get_connect\http\src\response\response.dart one (it's already existed alone there).

Pre-launch Checklist

• [x] I updated/added relevant documentation (doc comments with ///).
• [x] I added new tests to check the change I am making or feature I am adding, or @jonataslaw said the PR is test-exempt.
• [x] All existing and new tests are passing.