Add parsing logic for User-Agent headers (#5645)

* feat(ts_telemetry): add parsing logic for user agent headers

* feat(ts_telemetry): update gRPC observability for user-agent headers

* feat(ts_telemetry): add observation tags

* feat(ts_telemetry): Resolved comments

* feat(ts_telemetry): Removed loop variable capture

* feat(ts_telemetry): Updated userAgentKey to be inline

* feat(ts_telemetry): Add support for userAgent as per RFC 9110

* feat(ts_telemetry): Resolved comments

* Fix newline

* feat(ts_telemetry): Moved user-agent parsing to interceptor

* feat(ts_telemetry): Added user-agent parsing complex test case

* Update userAgentsKey comment

Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>

* feat(ts_telemetry): Updated changelog

* feat(ts_telemetry): Resolved comments

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Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>

internal/proto/controller/api/services/v1/authtokens_service.proto

@@ -49,7 +49,7 @@ service AuthTokenService {
 }
 
 message GetAuthTokenRequest {
-  string id = 1; // @gotags: `class:"public"`
+  string id = 1; // @gotags: `class:"public" eventstream:"observation"`
 }
 
 message GetAuthTokenResponse {