Fix Integer Overflow in Header Processing

[nerddtvg]

Fix Integer Overflow in Header Processing

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When MaxRequestHeadersTotalSize is set to int.MaxValue, an integer overflow occurs inside Http1Connection forcing connections to fail.

Description

A basic cast from int to long prior to the addition will solve this. I have attempted to include a Unit test, however I am unable to run unit tests to verify if this does in fact work as expected.

Fixes #41756

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