Automatic weights documentation (!222)

* fix no weight

* add const documentation

* refactor error handling

* refactor doc generation

* refactor using if let chaining

* add generic constructor

* add automatic max block weight from metadata

* remove all unwrap

* update docs

* add extrinsic base weight overhead

* update metadata

* fix readability

* add weights to doc

* fix  weight analyzer

* add max_block_weight

* add to workspace

* rework as a lib

* update all weights

* fix overhead benchmark

* add relative weight

* fix weight evaluation with complexity parameters

* add weights computation from weight files