[Feature] Add new stopping rule to matrix reasoning and mental rotation

[CCuskley]

For both Matrix Reasoning and Mental Rotation:

We want to end the task for users that have accuracy over the last 10 trials of <40%, i.e., they need to have gotten at least 4 of the last ten trials correct to continue. This should only kick in after 10 trails, so e.g.,

• On completion of the 10th trial, check performance over the last ten trails, if it's <4/10, end the task
• Perform the same check on every subsequent trial over window of previous 10 trials, if <4/10, end the task

[mcfrank]

I think we also want to do this for Mental Rotation.