Support error_arg for allow_rename = FALSE as well

[olivroy]

Closes #336, follow-up to #350

See comments from review in #358 (comment)

[DavisVaughan]

Maybe construct the message inside the if branch, but then fall through to a single call to cli_abort() so we dont duplicate the class name? (that feels like a place where we could make a typo to get out of sync). Maybe like

message <- "Can't rename variables in this context."

if (!is.null(error_arg)) {
  message <- c(message, i = cli::format_inline("{.arg {error_arg}} can't be renamed."))
}

cli::cli_abort(
  message,
  class = "tidyselect:::error_disallowed_rename",
  call = call
)

(Or maybe apply this general idea to the final error message that incorporates the expr)

[olivroy]

Good idea! I caught a copy paste typo while working on this.

I applied a similar logic to another duplicated error class I created

[lionel-]

In that case it's good practice to still interpolate message in a string like this:

cli::cli_abort(
  "{message}",
  class = "tidyselect:::error_disallowed_rename",
  call = call
)

This prevents unexpected interpolation/interpretation of components of messages, esp. if it comes from external sources (little bobby tables).

[lionel-]

oh but here it's not as straightforward because we're adding an element to the vector... I'm just going to revert this change then.

[lionel-]

Thanks for all these!