router: allow from_str on Confirmation that is not for FromStr

while usually this would improve ergonomics, in this case it isn't
clear whether all uses of `FromStr` would be considered valid here.
renaming the function would also make the type more confusing to use
as `from_str_with_default` also exists, so keep this for consistency.
this ignores a clippy lint [1].

[1]:
https://rust-lang.github.io/rust-clippy/master/index.html#should_implement_trait

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>

proxmox-router/src/cli/mod.rs

@@ -117,6 +117,7 @@ impl Confirmation {
     /// let answer = Confirmation::from_str("bogus");
     /// assert!(answer.is_err());
     /// ```
+    #[allow(clippy::should_implement_trait)]
     pub fn from_str(input: &str) -> Result<Self, Error> {
         match input.trim() {
             "y" | "Y" => Ok(Self::Yes),