[WIP] add average/integral/sum diagnostic output

[BenWibking]

Description

This adds the DiagConditional diagnostic from PelePhysics.

It computes the volume average, volume integral, or sum of a variable. This operation is optionally filtered by and/or conditioned on other variables, and outputs it to a text file at periodic intervals while a simulation is evolved. Only 1D conditional distributions are computed (higher dimensions are not implemented).

Mass-weighted averages or integrals are NOT yet supported for this diagnostic.

If an unconditioned volume average, volume integral, or sum is desired, you can condition on a "dummy variable" and set the number of bins of the conditional distribution to 1. This is equivalent to the unconditioned value. A future PR will remove the need for this workaround.

Example usage to find the (unconditioned) volume average temperature (and standard deviation):

quokka.condTemp.type = DiagConditional             # Diagnostic type
quokka.condTemp.file = condTemp                    # Output file prefix
quokka.condTemp.int  = 10                          # Frequency (as step #) for performing the diagnostic
quokka.condTemp.conditional_type = Average         # Conditional type: Average, Integral or Sum
quokka.condTemp.field_names = temperature          # List of variables to be averaged, integrated, or summed
quokka.condTemp.nBins = 1                          # Number of bins for the conditioning variable
quokka.condTemp.condition_field_name = gasDensity  # Conditioning variable name

Example usage to find the volume average temperature (and standard deviation) conditioned on (i.e., as a function of) gas density:

quokka.condTemp.type = DiagConditional             # Diagnostic type
quokka.condTemp.file = condTemp                    # Output file prefix
quokka.condTemp.int  = 10                          # Frequency (as step #) for performing the diagnostic
quokka.condTemp.conditional_type = Average         # Conditional type: Average, Integral or Sum
quokka.condTemp.field_names = temperature          # List of variables to be averaged, integrated, or summed
quokka.condTemp.nBins = 50                         # Number of bins for the conditioning variable
quokka.condTemp.condition_field_name = gasDensity  # Conditioning variable name

Note: Conditioning always uses linear-spaced bins (log-spaced bins are not yet supported).

Related issues

N/A

Checklist

Before this pull request can be reviewed, all of these tasks should be completed. Denote completed tasks with an x inside the square brackets [ ] in the Markdown source below:

• I have added a description (see above).
• I have added a link to any related issues see (see above).
• I have read the Contributing Guide.
• I have added tests for any new physics that this PR adds to the code.
• I have tested this PR on my local computer and all tests pass.
• I have manually triggered the GPU tests with the magic comment /azp run.
• I have requested a reviewer for this PR.