geoip: allow extracting the client IP address from a custom request header

[agrawroh]

Description

This PR adds a new ip_address_header which could be used to provide the client IP address instead of computing it using XFF hops. It's valuable in cases where we trust the first layer to correctly determine the client IP and then provide that as a header.

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Commit Message: geoip: allow extracting the client IP address from a custom request header
Additional Description: Adds a new ip_address_header which could be used to provide the client IP address instead of computing it using XFF hops.
Risk Level: Low
Testing: Added Unit + Integration Tests
Docs Changes: Added
Release Notes: Added

[repokitteh-read-only]

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Please mark your PR as ready when you want it to be reviewed!

🐱

Caused by: #42416 was opened by agrawroh.

see: more, trace.

[repokitteh-read-only]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/).
envoyproxy/api-shepherds assignee is @wbpcode
CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

🐱

Caused by: #42416 was opened by agrawroh.

see: more, trace.