Add a knob to make per_connection_buffer_limit_bytes configurable

[arkodg]

          Interesting discussion [here](https://github.com/envoyproxy/envoy/issues/8448) on compression performance and buffer sizing. Should we make `per_connection_buffer_limit_bytes` configurable as part of this issue? 

I can also think of future use cases that include buffering filters (ext-auth with body, WAF, ext-proc, lua, buffer) that should be part of the Envoy Gateway scope and require buffer size tuning.

Originally posted by @guydc in #2451 (comment)

Currently default to 32Kb
#1306

[yaelShechter]

@arkodg Please assign to me

[github-actions]

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