[Feature Request]: Extend `within` to accept a custom parameter that links all lines to a dataname

### Feature description

Extend `within.qenv(data, expr, links_to = NULL, ...)` so that `links_to` parameter will hint the code parser

The goal is that all the code in expr is hinted to one dataname (?or more?).

The `get_code` below would output the same code.

``` r
library(teal.code)
library(teal.data)

data_within <- teal_data() |> within({
options("AN_OPTION" = iris)
IRIS <- getOption("AN_OPTION")
}, links_to = "IRIS")

datanames(data_within) <- "IRIS"

get_code(data_within, datanames = "IRIS") |> cat()
#> IRIS <- getOption("AN_OPTION")

data_eval <- teal_data() |> eval_code("
options(\"AN_OPTION\" = iris) # @linksto IRIS
IRIS <- getOption(\"AN_OPTION\")
")

datanames(data_eval) <- "IRIS"

get_code(data_eval, datanames = "IRIS") |> cat()
#> options(AN_OPTION = iris)
#> IRIS <- getOption("AN_OPTION")
```

^{Created on 2024-02-20 with [reprex v2.0.2](https://reprex.tidyverse.org)}

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