13110 Companion: Add WeightToFee and LengthToFee Runtime API (#6536)

* Add WeightToFee runtime API impls

* Forgot a couple

* cargo update -p sp-io

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

* Use master Cargo.lock

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

* cargo update -p sp-io

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>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>