Add test to cover user-provided bounding box for volume calculations.

[aprilnovak]

This adds a test that shows that the OpenMC volume calculation correctly uses a bounding box provided by the user. We did have an error-check test which would throw an error if the lower left was greater than the upper right, but this test provides a user-given bounding box of volume 0.001, and we show that the stochastic calculation by OpenMC gives the same value.

[moosebuild]

Job Documentation on 3aef0d9 wanted to post the following:

View the site here

This comment will be updated on new commits.

[moosebuild]

Job Coverage on 3aef0d9 wanted to post the following:

Coverage

Coverage did not change

Full coverage report

This comment will be updated on new commits.