feat: Native tracing

[elliott-with-the-longest-name-on-github]

WIP.

This PR adds native tracing via @opentelemetry/api to SvelteKit.

It traces:

• load invocations
• action invocations
• handle and resolve invocations

@opentelemetry/api@^1.0.0 becomes an optional peer dependency. Users who want to opt into tracing can install the package along with their instrumentation packages and it will "just work"!

TODO:

• Configuration / extensibility -- what should we expose?
  • Just a global enable option?
  • An addAttributes option on the event to enable user-tagged attributes on the load spans?
    • IMO no, users can create child spans of their own inside of load which will be attached as children
  • Route-level tracing: boolean exports?
• Testing
• Find a way to tag clientside load functions with their node IDs?

---

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[elliott-with-the-longest-name-on-github]

closing for a stacked approach