Adds changeset

Author: calvincestari

.changesets/feat_feature_client_awareness_common_transport.md

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+###  ([PR #8503](https://github.com/apollographql/router/pull/8503))
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+Supporting a common transport mechanism for the Client Awareness and Enhanced Client Awareness values is more efficient than the current split between HTTP header (for Client Awareness) and `request.extensions` for Enhanced Client Awareness. This changeset allows clients to send both sets of values using the same method.
+
+By [@calvincestari](https://github.com/calvincestari).