Support UDPRoute with expression router

[randmonkey]

Is there an existing issue for this?

• I have searched the existing issues

Problem Statement

Split out of #4312
Kong 3.4 added support of expression router in L4 proxy. We could implement support of UDPRoute in gateway APIs.

Proposed Solution

• Translate UDPRoute into expression based Kong route when ExpressionRoutes feature gate is enabled, and Kong uses expression router

Additional information

No response

Acceptance Criteria

• KIC could translate UDPRoute to expression based Kong routes against Kong 3.4+ running with expression router