RFC: Labelling implicit effects into explicit capabilities

> [!NOTE]
> This is a request for comments in very early stages, feel free to comment/nitpick below.

Allow explicitly naming capabilities in effect sets in order to recover `summon`-style functionality, for example:
```scala
def foo(): Unit / {out: emit[Int], in: read[Byte], log, Exception[WrongFormat]} = {
val n: Int = in.read().toInt
do log(s"Saw: ${n}, emitting both it, and its square")
do emit(n)
out.emit(n * n)
}
```

then gets translated to
```scala
def foo() {out: emit[Int]} {in: read[Byte]} {$log: log} {$exc: Exception[WrongFormat]}: Unit = {
val n: Int = in.read().toInt {$exc}
$log.log(s"Saw: ${n}, emitting both it, and its square")
out.emit(n)
out.emit(n * n)
}
```

I think it's somewhat straightforward change in Parser, Namer, and ExplicitCapabilities, no changes at all from Core onwards, but I have no clue how big of a change this would be for Typer (I hope it's easy, but I can't really tell for sure).

As a bonus, this allows the LSP to come up with names, show them as inlay hints, and then we can even mention them in error messages.