Strip ANSI from the target of {.url} hyperlinks

[taekop]

With hyperlinks enabled, {.url} containing a substitution puts ANSI escapes into the link target:

options(cli.hyperlink = TRUE, cli.ansi = TRUE)
test <- "path"
cli::format_inline("{.url https://example.com/{test}}")

The target was https://example.com/\033[3mpath\033[3m, because the substituted value is italicised by the .url style before the whole string is passed to the link builder. Clicking it opens https://example.com/%1B%5B3mpath%1B%5B3m.

make_link_url() now strips ANSI from the target. The displayed text is unchanged, and so is the output for {.url} without substitutions, vectors, already-linked values, and with hyperlinks off.

Closes #757

[gaborcsardi]

Thanks!