[Variant] Support array access when parsing `VariantPath`

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

• As shown in Add example of parsing field names as VariantPath #8945

You can create a VariantPath from a string like this:

let path = VariantPath::from("city.store");

However, that format does not currently support selecting array elements

So for example, there is no way to parse the equivalent of this (select the title from the 4th book): city.store.books[3].title

Describe the solution you'd like
I would like to be able to do something like

VariantPath::from("city.store.books[3].title");

And get the equivalent of

VariantPath::from("city")
  .join("store")
  .join("books")
  .join(3)
  .join("title")

Describe alternatives you've considered

Additional context

[foskey51]

take

[alamb]

label_issue.py automatically added labels {'parquet-variant'} from #9012