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

[m7pr]

{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_namesstates: This is equivalent tostats::setNames()`, with more features and stricter argument checking.
• rlang::parse_expr -> substitute with base::parse.
  • Documentation of rlang::parse_exprstates 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 #194