Investigate dynamic generation of methods

[emostov]

As it stands, txwrapper methods are hardcoded and take a lot of boiler plate. This design was initially chose in order to create the easiest possible experience for library users as having the method arguments + documentation hard coded was hypothesized to make users experience easier.

An alternative to hardcoding would be having some dynamic generation.

Some ideas:

• Create JSON file with necessary info for methods and read in the info at runtime
• Create a script that scrapes metadata and spits out TS bindings code, something similar to polkadot-types-from-chain script that generates interfaces such as: https://github.com/AcalaNetwork/acala.js/blob/master/packages/types/src/interfaces/augment-api-tx.ts
• Have a script that generates code for the methods based on metadata.

I think the main considerations is that the solution should 1) not degrade runtime performance 2) should not break the existing API and 3) it should be very easy for new users navigate

cc @TarikGul

[emostov]

dupe with #44