* update header value options to convert append to envoy v3's append action

* update tests to expect appendAction

* remove focused test

* Update append description

* add changelog

* add extra informatnion on header append/removal docs

* Apply suggestions from code review

Co-authored-by: Art <artberger@users.noreply.github.com>

* Update docs/content/guides/traffic_management/request_processing/append_remove_headers/_index.md

Co-authored-by: Art <artberger@users.noreply.github.com>

* Update docs/content/guides/traffic_management/request_processing/append_remove_headers/_index.md

Co-authored-by: Art <artberger@users.noreply.github.com>

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Co-authored-by: soloio-bulldozer[bot] <48420018+soloio-bulldozer[bot]@users.noreply.github.com>
Co-authored-by: Art <artberger@users.noreply.github.com>

* add most_specific_header_mutations_wins route config option

* translate and add MostSpecificHeaderMutationsWins to translator_test

* add changelog

* add skipCI-kube-tests:true directive

* add header manipulation order e2e tests and expose routeTable in testContext's testClients

* codegen

* Add section in docs to include mostSpecificHeaderMutationsWins

* remove skipCI-kube-tests:true directive

* review comment updates

* Apply suggestions from code review

Co-authored-by: Art <artberger@users.noreply.github.com>

* review comment updates pt 2

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Co-authored-by: soloio-bulldozer[bot] <48420018+soloio-bulldozer[bot]@users.noreply.github.com>
Co-authored-by: Art <artberger@users.noreply.github.com>