Generic system scalar Depends on PR#328

[ke7kto]

Adds a generic system scalar kernel that handles the time-dependent mass balance of system components. Closes #329
Depends on PR#328

Reason

The fuel cycle examples are unwieldy and prone to copy-paste errors. Adding a custom scalar kernel will allow easier extensibility for specific component and system modeling.

Design

A new templated kernel which allows functor inputs and coupled variables to determine the residual. Assumes first-order dependence on "input" variables.

Impact

Re-implements the fuel cycle capabilities in a more explicit way.

[ke7kto]

This should be ready-to-go, but it depends on an open PR

[moosebuild]

Job Documentation, step Sync to remote on 33faac6 wanted to post the following:

View the site here

This comment will be updated on new commits.

[simopier]

You can rebase this PR now that #328 is merged.

[moosebuild]

Job Build test summary, step Build test summary on 33faac6 wanted to post the following:

Test summary

Compared against 6319488 in job civet.inl.gov/job/3423721.

Added tests

Test	Time (s)
test:fuel_cycle_Abdou.fuel_cycle_kernel	7.33
test:fuel_cycle_Abdou.fuel_cycle_kernel_AD	2.14
test:fuel_cycle_Abdou.fuel_cycle_kernel_inputs_mismatch	0.87
test:fuel_cycle_Abdou.fuel_cycle_kernel_invalid_coupling	0.76
test:fuel_cycle_Abdou.fuel_cycle_kernel_implicit	0.43
test:fuel_cycle_Abdou.fuel_cycle_kernel_ss	0.43

[simopier]

@ke7kto, how do you want to tackle this? Do you want to fix the tests or should I start reviewing this?

[simopier]

Do not change these here unless you expect this PR to change their results (which I do not think it should unless I'm missing something).

[simopier]

Do not change these here unless you expect this PR to change their results (which I do not think it should unless I'm missing something).

[simopier]

Do not change these here unless you expect this PR to change their results (which I do not think it should unless I'm missing something).

[simopier]

Need any help on this one, @ke7kto?