[post frontend-backend split] Advice with sealed phase in the frontend

[ed255]

Currently the Advice type used in the frontend comes from the middleware, which exposes the phase as a u8. In order to hide this from the user we need to have copy of the Advice type internal to the frontend with a sealed phase.

Probably this means also brining duplicates for Fixed, Instance, ColumnType and Any into the frontend. After this, the corresponding types in the middleware can be greatly simplified.

Blocked by #290

[duguorong009]

I believe this issue has already been addressed in #300 .
Hence, I propose that we close this issue as it is resolved or no longer needed.

What do you think? @ed255

[ed255]

I believe this issue has already been addressed in #300 . Hence, I propose that we close this issue as it is resolved or no longer needed.

What do you think? @ed255

You're totally right! Thanks for checking this, I'll just close the issue :)