FixedPoint should be a LogicStructure

[mkorbel1]

Motivation

The components of a FixedPoint should be independently accessible (sign, m, and n). A good way to do this is by making it a LogicStructure, like FloatingPoint is.

Also, we should probably change variable names m and n so that it is clear they represent the widths, so that m and n can be left to represent the components.

Desired solution

• Convert FixedPoint into a LogicStructure
• Make existing m and n into mWidth and nWidth.
• Make m and n and sign now point to elements of the structure

Alternatives considered

No response

Additional details

No response