Generalize integrand f to any callable

[mikeingold]

Changes

• Removes requirement that integrand f be of type Function
  • Closes Generalize integrand f to any callable #132
• Updates relevant docs
• Updates tests to include coverage of callable struct as integrand.

[github-actions]

Benchmark Results

	main	2913f80...	main/2913f807a41d1c...
Differentials/Differential	0.239 ± 0.0011 μs	0.239 ± 0.001 μs	0.996
Differentials/Jacobian	0.205 ± 0.001 μs	0.206 ± 0.001 μs	0.995
Integrals/Meshes.BezierCurve/Scalar GaussKronrod	22.4 ± 0.04 ms	22.9 ± 0.1 ms	0.976
Integrals/Meshes.BezierCurve/Scalar GaussLegendre	21.4 ± 0.043 ms	21.9 ± 0.066 ms	0.975
Integrals/Meshes.BezierCurve/Scalar HAdaptiveCubature	22.6 ± 0.057 ms	23.2 ± 0.072 ms	0.976
Integrals/Meshes.BezierCurve/Vector GaussKronrod	22.4 ± 0.04 ms	23 ± 0.073 ms	0.973
Integrals/Meshes.BezierCurve/Vector GaussLegendre	21.4 ± 0.039 ms	21.9 ± 0.12 ms	0.975
Integrals/Meshes.BezierCurve/Vector HAdaptiveCubature	22.6 ± 0.045 ms	23.2 ± 0.048 ms	0.974
Integrals/Meshes.Segment/Scalar GaussKronrod	1.19 ± 0.0061 μs	1.21 ± 0.01 μs	0.989
Integrals/Meshes.Segment/Scalar GaussLegendre	8.53 ± 0.18 μs	8.52 ± 0.22 μs	1
Integrals/Meshes.Segment/Scalar HAdaptiveCubature	1.73 ± 0.061 μs	1.74 ± 0.048 μs	0.993
Integrals/Meshes.Segment/Vector GaussKronrod	3.42 ± 0.06 μs	3.38 ± 0.053 μs	1.01
Integrals/Meshes.Segment/Vector GaussLegendre	24.6 ± 0.55 μs	24.3 ± 0.5 μs	1.01
Integrals/Meshes.Segment/Vector HAdaptiveCubature	4.61 ± 0.083 μs	4.63 ± 0.09 μs	0.996
Integrals/Meshes.Sphere/Scalar GaussKronrod	0.0839 ± 0.00059 ms	0.0843 ± 0.00061 ms	0.995
Integrals/Meshes.Sphere/Scalar GaussLegendre	2.25 ± 0.0096 ms	2.25 ± 0.0091 ms	0.999
Integrals/Meshes.Sphere/Scalar HAdaptiveCubature	0.0599 ± 0.00025 ms	0.06 ± 0.00023 ms	0.999
Integrals/Meshes.Sphere/Vector GaussKronrod	0.116 ± 0.00077 ms	0.116 ± 0.00096 ms	0.999
Integrals/Meshes.Sphere/Vector GaussLegendre	3.72 ± 0.069 ms	3.6 ± 0.07 ms	1.03
Integrals/Meshes.Sphere/Vector HAdaptiveCubature	0.11 ± 0.0011 ms	0.11 ± 0.0011 ms	0.998
time_to_load	1.5 ± 0.011 s	1.47 ± 0.011 s	1.02

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 4 lines in your changes missing coverage. Please review.

Project coverage is 95.86%. Comparing base (cba39f0) to head (2913f80).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/specializations/Tetrahedron.jl	0.00%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #137   +/-   ##
=======================================
  Coverage   95.86%   95.86%           
=======================================
  Files          17       17           
  Lines         290      290           
=======================================
  Hits          278      278           
  Misses         12       12           

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[mikeingold]

The codecov/patch test fails because these changes touch the Tetrahedron methods, whose tests are currently tagged under extended/local-only testing.

[JoshuaLampert]

LGTM. Thanks!