Allow constants in `adv_map` definition

### Feature description

Currently the only way to create an advice map from the assembly code is to use the `Felt`s themselves. Here is the code fragment from the `grammar.lalrpop` file:
` "adv_map" <...> "=" "[" > "]" `

It would be very convenient to be able to use the constants in addition to felts, so changing the above code to something like:
` "adv_map" <...> "=" "[" > "]" `

### Why is this feature needed?

This feature will massively simplify the development of the new Agglayer functionality, namely the Keccak-based MMR frontier.

Its main algorithm requires to have a list of canonical zeros in memory, and the most efficient way to load them there is to use the advice map. These canonical zeros are generated as constants in a separate file, so for now they cannot be used as `adv_map` values.