Provide a post-fitting check in PDCalibration/FitPeaks for I/Sigma ratio.

[RichardWaiteSTFC]

Describe the solution you'd like Be able to provide minimum I/sigma in PDCalibration (and possibly FitPeaks) for inclusion of peak centres in fit to determine diffractometer constants.

Additional context Came up during discussion of PR #35094. @bolotovskyr has opened this issue as a story in the Engineering Workflow Management system: Story 356 [Enabler] Provide a post-fitting check in PDCalibration/FitPeaks for I/Sigma ratio