cipher: resolve `clippy::needless_lifetimes` lint

[newpavlov]

Right now we have methods like this:

fn encrypt_padded_inout<'inp, 'out, P: Padding<Self::BlockSize>>(
    &self,
    data: InOutBufReserved<'inp, 'out, u8>,
) -> Result<&'out [u8], PadError> { .. }

The Clippy lint suggests to write it like this:

fn encrypt_padded_inout<'out, P: Padding<Self::BlockSize>>(
    &self,
    data: InOutBufReserved<'_, 'out, u8>,
) -> Result<&'out [u8], PadError> { .. }

In my understanding, strictly speaking, it's a breaking change, so it should be done as part of cipher v0.5.