[WIP] Deprecate making a literal followed by immediate bit extract

Using .U as an example:

The API for constructing a literal of a set width is as follows:

123.U(8.W)

The problem is that it is very easy to forget the `.W`:

123.U(8)

This is actually equivalent to creating a literal then immediately
following it with bit extraction (.apply):

123.U.apply(8)

This is now deprecated by adding a form of .U that accepts a BigInt.