codegen: `RuntimeClientPlugin` not having access to a `SymbolProvider`

`RuntimeClientPlugin` is used for a variety of codegen points, e.g. middleware registration:

https://github.com/aws/smithy-go/blob/7be1336444e91daf7a4d27419910a9ca0518230d/codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/integration/RuntimeClientPlugin.java#L138

However, middleware registration typically needs access to a symbol provider to correctly get the name of functions and such.

There should be a way to expose the symbol provider in `RuntimeClientPlugin`.

Start in codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/integration/RuntimeClientPlugin.java around line 138, then inspect the middleware registration codegen points that use the plugin. Determine how a SymbolProvider should be exposed to those integrations; done when middleware registration can obtain the needed function names through the plugin API.

Written by the indexing model from the issue text.