Remove config provider interface pointer

[jlegrone]

What was changed

The WithConfigProvider start option has been updated to accept a ConfigProvider argument (an interface) rather than *ConfigProvider (a concrete type). This is a breaking change for users of the github.com/temporalio/ui-server/server/server_options package.

Why?

Pointers to interfaces can be tricky to work with; see this thread for more background: https://stackoverflow.com/questions/44370277/type-is-pointer-to-interface-not-interface-confusion

Checklist

1. Closes

2. How was this tested:

3. Any docs updates needed?