Pvf thiserror (#2958)

resolve #2157 

- [x] fix broken doc links
- [x] fix codec macro typo
https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/node/core/pvf/common/src/error.rs#L81
(see the comment below)
- [x] refactor `ValidationError`, `PrepareError` and related error types
to use `thiserror` crate

## `codec` issue

`codec` macro was mistakenly applied two times to `Kernel` error (so it
was encoded with 10 instead of 11 and the same as `JobDied`). The PR
changes it to 11 because

- it was an initial goal of the code author
- Kernel is less frequent than JobDied so in case of existing error
encoding it is more probable to have 10 as JobDied than Kernel

See https://github.com/paritytech/parity-scale-codec/issues/555

----
polkadot address: 13zCyRG2a1W2ih5SioL8byqmQ6mc8vkgFwQgVzJSdRUUmp46