Develop a strategy regarding backwards compatibility

[Niederb]

We should discuss and document how/if we want to support breaking changes (such as #777) by providing backwards compatibility. Some considerations:

• The code gets cluttered quickly if there are lots of conditional compilation instructions
• Running the testing for each option gets out of hand quickly
  • If one is strict we would also need to run our tests for each supported polkadot version
• Different chains (polkadot, kusama, rococo) might have a different configuration and therefore it would be important for our client