fix(opentelemetry-instrumentation-http): Support http headers as array

[yotamN]

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Which problem is this PR solving?

The http package in Node actually supports receiving the headers as an array of strings. The definition file was updated accordingly and there is an open PR for the documentation as well.

Short description of the changes

Update NodeJS definition file and add support for headers array.

Type of change

• [X] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Still working on the unit test, something is not working for me :(

Checklist:

• [ ] Followed the style guidelines of this project
• [ ] Unit tests have been added
• [ ] Documentation has been updated