[FIRRTL] Annotations Targeting Aggregates of Probes Not Found

Nobody has claimed this yet.

Annotation resolution of aggregates of probes should produce a better error message. Currently, this fails to find the "name". The actual issue is that it is an annotation targeting a probe.

Consider:

```
FIRRTL version 3.3.0
circuit Foo: %[[
{"class":"firrtl.transforms.DontTouchAnnotation","target":"~Foo|Foo>a"},
{"class":"firrtl.transforms.DontTouchAnnotation","target":"~Foo|Foo>b"}
]]
module Foo:
output a: Probe>[1]
output b: {a: Probe>}
```

This produces:

```
firrtl-snippets/ProbeAnnotations.fir:2:1: error: cannot find name 'a' in Foo
circuit Foo: %[[
^
firrtl-snippets/ProbeAnnotations.fir:2:1: error: Unable to resolve target of annotation: {class = "firrtl.transforms.DontTouchAnnotation", target = "~Foo|Foo>a"}
circuit Foo: %[[
^
firrtl-snippets/ProbeAnnotations.fir:2:1: error: cannot find name 'b' in Foo
circuit Foo: %[[
^
firrtl-snippets/ProbeAnnotations.fir:2:1: error: Unable to resolve target of annotation: {class = "firrtl.transforms.DontTouchAnnotation", target = "~Foo|Foo>b"}
circuit Foo: %[[
^
```

Start with the reproducer in firrtl-snippets/ProbeAnnotations.fir and trace annotation resolution for the two Probe targets. Compare the current diagnostics with the issue's example; done means aggregate Probe annotations no longer produce the misleading cannot-find-name error and report the target-resolution failure accurately.

Written by the indexing model from the issue text.