[Feature Request]: remove `{rlang}` from `{teal.transform}`

`{rlang}` is used just a couple of times in 3 cases

- `rlang::is_empty` -> substitute with `length(x) == 0`
- `rlang::set_names` -> substitute with `stats::setNames`.
- Documentation of rlang::set_names` states: This is equivalent to `stats::setNames()`, with more features and stricter argument checking.
- `rlang::parse_expr` -> substitute with `base::parse`.
- Documentation of `rlang::parse_expr`states they are barely the same and the only difference is that: `parser_expr`, unlike `base::parse`, never retain source reference information, as doing so is slow and rarely necessary. We can substitute with `parser(keep.source = FALSE)`.

Consider if we can substitute those with equivalents from `{base}` package.

Part of https://github.com/insightsengineering/teal.transform/issues/194