[Feature Request] Support passing callsite information

Nobody has claimed this yet.

I'd love to be able to get information about the callsite of the comptime, and potentially introspect a layer or two up the callstack. At a basic level, this would be something like { filepath: string, lineNumber: number }, but I imagine could include additional information such as surrounding AST.

An example of what this would be useful for is to inject callsite information automatically into OpenTelemtetry without having to do the expensive and inaccurate (in the case of bundling) operation of retrieving a stacktrace at runtime.

## Motivating examples:
```ts
// src/myfile.ts
import { $autoFunctionLabel, $autoCallsite, $autoLine, $autoSmartAssertCondition } from 'my-lib'

class MyClass {
myFunction() {
const span = tracer.startSpan($autoFunctionLabel())
span.setAttribute("callsite", $autoCallsite())

const x = 5;
const y = 10;

assert(x == y, `Assertion failed! Context: "${$autoLine()}"`)
// a more intelligent variant
assert(x == y, `Assertion failed! Condition: "${$autoSmartAssertCondition()}"`)
}
}

// transforms into

class MyClass {
myFunction() {
const span = tracer.startSpan("MyClass.myFunction")
span.setAttribute("callsite", "src/myfile.ts:42")

const x = 5;
const y = 10;

assert(x == y, `Assertion failed! Context: "assert(x == y, \`Assertion failed! Context: \${$autoLine()}\`)"`)
// a more intelligent variant
assert(x == y, `Assertion failed! Condition: "x == y"`)
}
}
```

(copied over from my issue on unplugin-macros https://github.com/unplugin/unplugin-macros/issues/132 😄 that I never got around to implementing)

Start by reading the existing comptime integration with Vite and Rolldown and tracing how TypeScript callsites are transformed at build time. Define the smallest supported callsite shape first, then compare the result against the motivating examples for filepath, line number, function label, and source context.

Written by the indexing model from the issue text.