Add definable for codec

[Licenser]

Describe the problem you are trying to solve

Right now codecs can't be configured or defined, this means every codec has to be hard coded instead of allowing us to integrate it in the standard library.

Describe the solution you'd like

As with all other defines we would have define codec.

Notes

• it is worth discussing if we need a create here as it is created when it's used in a connector.
• it's also worth discussing how we would change the define connector to allow codec configuration
• No examples are given yet as this is a tracking ticket for now.

[mfelsche]

To make matters worse, there is a new instance of both codec and postprocessor or preprocessor created for every new stream.

[Licenser]

oh 😭