Customize bus number

[TKone7]

Hey, thanks a lot for this custom component. I realized that custom_components/mcp23017/const.py defines a constant number for the bus being used /dev/i2c-#. In my case this is not sufficient and I would think it would be best to let this be configured.

Would you accept a PR that makes this a config?

[jpcornil-git]

Sure/happy to support, just make sure it is optional, support config flow (configuration.yaml not a must), defaults to current bus and doesn't break existing configflow/configuration.yaml configurations.

There are two options wrt bus number configuration:

• it remains a global settings, i.e. just an option to change the current default (low hanging fruit)
• it becomes a component property (better/more complex change but it should only affect the toplevel logic as MCP23017 class has been prepared to support that already)