App port changes

[NikhitaR-IFX]

Summary

To get drag and drop functionally as well working, I had to refactor the enablement a bit. Following are the main changes:

a) Sources:

1. Refactored to store model state internally.
2. Allow multiple instances to be created (multiple model support).
3. Added two helper functions for user to get current model's input and output dimensions.

b) Makefile:

1. Added custom clean target for Makefile to automatically clean caches alongwith build/ and .mpy file.
2. Override gcc path with our installed path.

I have removed the model.c/.h as this is not part of our sources and something that a user will generated from studio.

You can help reviewing technically (from MPY eyes :) ) for now. With python script also released, I will open a final PR which will be easier to test and would anyway use the sources here.

Note: For now the changes are merged to mpy-dc-int which was the branch supposed to be maintained for all DEEPCRAFT related enablement since this branch is like ports-psoc6-main but without network and FreeRTOS enabled. In case we are able to improve here, I will bring all the changes to required branch then.

[jaenrig-ifx]

All good 👍 We can discuss if there is anything on CI on-target that is worth to add
But that depends on next steps 😉.
And let´s see how/when/if this is merged again main.