Translate UpstreamSettingsPolicy to data plane configuration

[kate-osborn]

As a user
I want NGF to take my configuration for an UpstreamSettingsPolicy and transform it into data plane configuration within NGF
So that NGF can then translate those settings into NGINX configuration
And so that NGF maintains an abstraction layer between data plane configuration and the specific data plane NGF uses.

Acceptance

• When an UpstreamSettingsPolicy is created, NGF reads the configuration from the policy and translates it into data plane configuration.
• The data plane configuration is stored within NGF.

[github-actions]

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