Restore EnumerableSet.enumerate

[nventuro]

This function was removed in #2160 due to issues with casting arrays of different types.

This can be achieved using assembly:

bytes32[] x = ...;
uint[] ret;
assembly { ret := x }

However, creating an assembly block brings all assembly keywords into scope, which causes shadowing warnings to be emitted by the compiler due to the existence of functions with names such as add in the same scope.

We should devise a way to bring enumerate back without these warnings being triggered.

[thegostep]

The better approach would be to store all base data as uint and delegate implementation of types to the user

[thegostep]

In any case, my solution here does not trigger a warning: #2295

[frangio]

delegate implementation of types to the user

We're avoiding this because it can easily result in unsafe casting that we'd rather keep internal to the library.

[ernestognw]

Should've been closed by #2768