[GeoMechanicsApplication] Create exit criterion for c-phi process for too small reduction steps

[rfaasse]

As a user, I want my C-Phi reduction to stop when the reduction increment is small enough, such that the process does not spend time in gaining unnecessary precision levels.

Acceptance Criteria
Given the user runs a C-Phi procedure
When the reduction increment is smaller than 0.1% (meaning the change in $c$ and $\tan{\phi}$ is < 0.1%)
Then the procedure exits and reports the latest safety factor