Differentiate between custom-instrumented values and SDK-auto-instrumented ones in UI

### Problem Statement

When debugging problems with Sentry, it would be helpful to know whether a value, for example a `tag` or a `transaction`, is auto-instrumented or custom-instrumented. It would ideally apply across errors and transactions alike.

If I know something is custom-instrumented, I'd immediately go to my codebase to see where developers created or modified it. But if something is auto-instrumented, I'd spend more time in the docs.

I understand that this could be tricky. Where do you draw the line between auto vs. custom instrumented? For example, if it's a custom instrumented transaction, but I modify fields in the event before it's sent, is that considered 'auto' or 'custom'? 🤷

### Solution Brainstorm

Mark auto-instrumented values as auto-instrumented in the UI somehow, so that the user can tell whether someone on their team deliberately caused the span/tag/etc to be sent in, or whether Sentry SDK automatically instrumented it.

When I say 'the UI', I mean anywhere the custom span/tag/etc shows up, for example in an Issue, Transaction, or Discover.

### Product Area

Other