Use same `fmt` and `clippy` configs as in Polkadot (#3004)

* Copy rustfmt.toml from Polkadot master

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Format with new config

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Add Polkadot clippy config

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Update Cargo.lock

Looks like https://github.com/paritytech/polkadot/pull/7611 did not
correctly update the lockfile. Maybe a different Rust Version?!

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

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Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>