Fix gradients of parametric expressions

[MilesCranmer]

Due to the conversion of ParametricExpression to Node within the parametric expression evaluation, the gradients with respect to constants in the expression were not being propagated. This fixes it with a new ChainRulesCore.rrule.

[coveralls]

Pull Request Test Coverage Report for Build 9725012512

Details

• 11 of 11 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 95.463%

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Totals
Change from base Build 9653484196:	0.02%
Covered Lines:	2167
Relevant Lines:	2270

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💛 - Coveralls

[github-actions]

Benchmark Results

	master	a2f5673...	master/a2f567337d1d3a...
eval/ComplexF32/evaluation	7.51 ± 0.46 ms	7.44 ± 0.46 ms	1.01
eval/ComplexF64/evaluation	9.8 ± 0.74 ms	9.75 ± 0.7 ms	1.01
eval/Float32/derivative	11 ± 1.7 ms	10.8 ± 1.6 ms	1.02
eval/Float32/derivative_turbo	10.9 ± 1.8 ms	10.9 ± 1.6 ms	1
eval/Float32/evaluation	2.76 ± 0.22 ms	2.79 ± 0.21 ms	0.988
eval/Float32/evaluation_bumper	0.593 ± 0.013 ms	0.534 ± 0.014 ms	1.11
eval/Float32/evaluation_turbo	0.712 ± 0.032 ms	0.703 ± 0.03 ms	1.01
eval/Float32/evaluation_turbo_bumper	0.594 ± 0.013 ms	0.534 ± 0.014 ms	1.11
eval/Float64/derivative	14.1 ± 0.64 ms	14 ± 0.61 ms	1.01
eval/Float64/derivative_turbo	14.3 ± 0.65 ms	14.8 ± 1 ms	0.965
eval/Float64/evaluation	2.94 ± 0.24 ms	2.91 ± 0.23 ms	1.01
eval/Float64/evaluation_bumper	1.3 ± 0.044 ms	1.2 ± 0.043 ms	1.09
eval/Float64/evaluation_turbo	1.2 ± 0.062 ms	1.19 ± 0.06 ms	1.01
eval/Float64/evaluation_turbo_bumper	1.3 ± 0.046 ms	1.2 ± 0.046 ms	1.08
utils/combine_operators/break_sharing	0.0408 ± 0.0013 ms	0.0414 ± 0.0013 ms	0.988
utils/convert/break_sharing	28.5 ± 1 μs	29.1 ± 1.1 μs	0.979
utils/convert/preserve_sharing	0.129 ± 0.0028 ms	0.132 ± 0.0032 ms	0.98
utils/copy/break_sharing	29.5 ± 0.99 μs	29.4 ± 1 μs	1.01
utils/copy/preserve_sharing	0.128 ± 0.0028 ms	0.132 ± 0.0032 ms	0.974
utils/count_constants/break_sharing	10.6 ± 0.16 μs	11.7 ± 0.2 μs	0.902
utils/count_constants/preserve_sharing	0.113 ± 0.0024 ms	0.116 ± 0.0026 ms	0.981
utils/count_depth/break_sharing	12.5 ± 0.22 μs	12.8 ± 0.22 μs	0.98
utils/count_nodes/break_sharing	9.97 ± 0.16 μs	10.3 ± 0.16 μs	0.968
utils/count_nodes/preserve_sharing	0.115 ± 0.0025 ms	0.119 ± 0.0026 ms	0.969
utils/get_set_constants!/break_sharing	0.121 ± 0.0042 ms	0.122 ± 0.0043 ms	0.993
utils/get_set_constants!/preserve_sharing	0.323 ± 0.0082 ms	0.321 ± 0.0075 ms	1.01
utils/has_constants/break_sharing	4.72 ± 0.22 μs	4.38 ± 0.23 μs	1.08
utils/has_operators/break_sharing	1.6 ± 0.016 μs	1.78 ± 0.02 μs	0.9
utils/hash/break_sharing	0.0337 ± 0.00054 ms	0.033 ± 0.00048 ms	1.02
utils/hash/preserve_sharing	0.137 ± 0.0032 ms	0.137 ± 0.0027 ms	1
utils/index_constants/break_sharing	27.6 ± 0.71 μs	27.7 ± 0.67 μs	0.996
utils/index_constants/preserve_sharing	0.13 ± 0.0031 ms	0.131 ± 0.0028 ms	0.997
utils/is_constant/break_sharing	4.65 ± 0.22 μs	4.9 ± 0.22 μs	0.948
utils/simplify_tree/break_sharing	0.153 ± 0.015 ms	0.163 ± 0.016 ms	0.935
utils/simplify_tree/preserve_sharing	0.285 ± 0.016 ms	0.271 ± 0.017 ms	1.05
utils/string_tree/break_sharing	0.391 ± 0.013 ms	0.386 ± 0.011 ms	1.01
utils/string_tree/preserve_sharing	0.535 ± 0.017 ms	0.521 ± 0.014 ms	1.03
time_to_load	0.232 ± 0.0034 s	0.228 ± 0.0033 s	1.02