Get rid of need for explicit ubiquitous fuel pattern

[buzden]

Current generators of type Gen are explicitly finite. Thus, when we define recursive generators, we use fuel pattern everywhere, especially in derived generators. Actually, for simplicity, we use it always for derived generators, even when it is actually not needed.

By the way, using Fuel -> Gen ... instead of just Gen ..., we run into problems in the compiler, e.g. idris-lang/Idris2#2522

We could have a possibly-infinite generators using co-data inside and to provide fuel only at the end of the day, when producing particular values.

We need to decide whether this is useful to have a distinction between definitely finite and possibly infinite generators, or not. This distinction makes it easier to run finite generators (no fuel required) but makes generators combinations and derivation more complex.

[buzden]

Possibly, any implementation of this would be blocked by the need of something like #69, which, in its turn, also blocked by the behaviour of the compiler. This all is because as soon as we get rid of Fuel argument, we cannot analyse auto-implicit arguments at the call site of deriveGen macro