Add payment_queryFeeDetails RPC (#7692)

* Return FeeDetails in compute_fee_raw()

* Add payment_queryDetails rpc

* Simplify serde attribute a bit

* Fix line width check

* Use saturating_add()

* Move transaction payment rpc types to types.rs

* Add file header

* Fix test

* Update Cargo.lock

* Nit

* Apply the review suggestions

* .

* .

* Fix serde

* Fix rust doc

* .

* Update frame/transaction-payment/src/types.rs

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* Use NumberOrHex in fee details RPC

* Address review feedback

* Nits

* Update some docs

* Address review

* Update frame/transaction-payment/src/types.rs

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* Happy 2021

* Nit

* Address code review

* Remove needless bound

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>