HTTP/3: Use SETTINGS_MAX_FIELD_SECTION_SIZE setting

[JamesNK]

Kestrel is sending SETTINGS_MAX_FIELD_SECTION_SIZE to the client but it isn't using SETTINGS_MAX_FIELD_SECTION_SIZE sent by the client.

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We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. Because it's not immediately obvious that this is a bug in our framework, we would like to keep this around to collect more feedback, which can later help us determine the impact of it. We will re-evaluate this issue, during our next planning meeting(s).
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