Support retries

[arkodg]

Description:

Add retry settings to be able to retry making requests to a backend

Relates to

• GEP: Configurable Retries in HTTPRoute kubernetes-sigs/gateway-api#1731
• proposal: BackendTrafficPolicy #1821 (comment)
• feat Route Timeouts #1899 (comment)

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Any extra documentation required to understand the issue.

[zirain]

need something like TimeoutPolicy on upstream?

[arkodg]

@zirain, based on @kflynn's comment here we should try and implement in this project as a top level field within BackendTrafficPolicy

[zirain]

oh, may bad, there's only one client(the proxy) in ingress mode.
yes, we can put retries under BackendTrafficPolicy .

[tmsnan]

/assign