`from`: BLOCKED) It would be nice if we could make TryFrom assignment work

*On 2022-05-28 @recmo wrote in [`1ec2e50`](https://github.com/recmo/uint/commit/1ec2e50003548890260e8c06886f44fd826bc07b) “Recognize new tags”:*

BLOCKED) It would be nice if we could make TryFrom assignment work
for all Uints.
impl<
const BITS_SRC: usize,
const LIMBS_SRC: usize,
const BITS_DST: usize,
const LIMBS_DST: usize,
TryFrom> for Uint

type Error = ToUintError;

```rust
// fn from(t: T) -> Self {
// Self::try_from(t).unwrap()
// }
// }

// FEATURE: (BLOCKED) It would be nice if we could make TryFrom assignment work
// for all Uints.
// impl<
// const BITS_SRC: usize,
// const LIMBS_SRC: usize,
// const BITS_DST: usize,
// const LIMBS_DST: usize,
// > TryFrom> for Uint
// {
// type Error = ToUintError;

// fn try_from(value: Uint) -> Result {
// }
// }

```
*From [`src/from.rs:17`](https://github.com/recmo/uint/blob/1ec2e50003548890260e8c06886f44fd826bc07b/src/from.rs#L17)*