feat: add subgraph expressions and tracing attributes

[SkArchon]

Motivation and Context

This PR adds subgraph expressions and tracing attributes.

Subgraph ExpressionContext
The following is introduced. We only have a minimal expression context for subgraph as it stands. We introduce the following

subgraph:
  id # subgraph id
  name #subgraph name
  request
    error #subgraph error if any occurred
    clientTrace # we can add any future trace related params here without polluting the request interface
      connAcquireDuration

Add Tracing Attributes
We already have metric and telemetry attributes, however we do not have tracing attributes, which can only be used to add values to tracing or spans. This is introduced as customers might be interested in how long a connectionAcquire took for a subgraph.

Process subgraph expressions for telemetry
Like we have attributesWithAuth we introduce attributesWithSubgraph which is essentially attributes that use subgraph in the expression context. We separate these values out for all three of telemetry / tracing and metric attributes and process them for every subgraph call.

Process Subgraph Expressions In Logs And Tracing/Telemetry Attributes
We have expressions for router access logs, however we do not use expressions for the subgraph access logger right now, we add this feature and allow users to define subgraph access log expressions.

Checklist

• I have discussed my proposed changes in an issue and have received approval to proceed.
• I have followed the coding standards of the project.
• Tests or benchmarks have been added or updated.
• Documentation has been updated on https://github.com/wundergraph/cosmo-docs.
• I have read the Contributors Guide.

[github-actions]

Router image scan passed

✅ No security vulnerabilities found in image:

ghcr.io/wundergraph/cosmo/router:sha-477e5356821a4b564e82d897835ac543641a4027

[StarpTech]

LGTM