Explain the feature/fix

• Extended the http.Agent types to include the maxHeaderSize property.
• Set the global agent's maxHeaderSize to 16MB to allow larger request headers.

Does this PR introduce a breaking change

Screenshots

Ready-for-merge Checklist

• Expected files: all files in this pull request are related to one feature request or issue (no stragglers)?
• Does the change have appropriate unit tests?
• Did tests pass?
• Did you update or add any necessary documentation (README.md, WHY.md, etc.)?
• Was this feature demoed and the design review approved?