ENH: Allow the "Merge Twins" and/or "Find Twin Boundaries" filters to compute twin length or area fraction.

### Is there an existing plan for this?

- [x] I have searched the existing discussions, release notes, and documentation.

### Description of the Feature, Filter, or Functionality?

It is common for us to want to know the twin area (or length, if users have 2D EBSD scans or models) fraction, i.e., the ratio of grain boundary areas that share the twin orientation relationship to the total grain boundary area. The filter enhancement would add an array to the Cell Ensemble Attribute Matrix and report a float for the twin length or area fraction.

Although these filters currently work for only Sigma 3 grain boundaries in FCC materials, a very long term extension could be applying it to any special grain boundary desired by the user.

### Version

7.0.x (DREAM3DNX beta)

### What section did you foresee your suggestion falling in? [Further details may be required during triage process]

_No response_

### High Level Steps To Implement

Those filters already iterate through all the grain boundaries to determine misorientation across them. This enhancement would keep track of the area of those grain boundaries of interest (most commonly, the Sigma 3 grain boundaries) and then just divide this by the total sum of grain boundary area (or length, if users are working with a 2D EBSD scan or microstructure).

### Anything else?

_No response_

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct