Simplifying log density tests

[sunxd3]

the tests are not changed, but simplified and moved into one file.

instead of using DynamicPPL for reference values, now uses hardcoded values for BUGS model (still random for single distribution tests)

[coveralls]

Pull Request Test Coverage Report for Build 11209165134

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 27 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-1.5%) to 81.458%

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Files with Coverage Reduction	New Missed Lines	%
src/logdensityproblems.jl	1	88.89%
src/BUGSPrimitives/distributions.jl	6	21.9%
src/model.jl	20	78.99%

Totals
Change from base Build 11174395661:	-1.5%
Covered Lines:	1441
Relevant Lines:	1769

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💛 - Coveralls

[github-actions]

BridgeStan not found at location specified by $BRIDGESTAN environment variable, downloading version 2.5.0 to /home/runner/.bridgestan/bridgestan-2.5.0
Done!
Model dogs produces error: ErrorException("log_density() failed with exception: Exception: bernoulli_lpmf: Probability parameter is inf, but must be in the interval [0, 1] (in '/home/runner/work/JuliaBUGS.jl/JuliaBUGS.jl/benchmark/stan-example-models/bugs_examples/vol1/dogs/dogs.stan', line 37, column 6 to line 38, column 62)\n")

Model	Parameter Count	Data Count	Stan Density Time (µs)	Stan Density Gradient Time (µs)	JuliaBUGS Density Time with Graph Walk (µs)	JuliaBUGS Density Gradient Time with ReverseDiff.jl(compiled tape) (µs)
rats	65	150	5.5484	8.155	8097.69	91.395
pumps	12	10	1.02371	1.35568	205.122	6.7225
dogs	2	720	NA	NA	3543.8	198.99
seeds	26	21	2.52564	3.15256	805.659	21.84
surgical_realistic	14	12	1.29059	1.69435	286.213	9.54467
magnesium	108	96	10.4995	12.0175	11155.2	99.024
salm	22	18	2.382	3.05911	574.558	13.46
equiv	15	20	2.553	3.53538	471.768	16.05
dyes	9	30	1.01466	1.39976	290.06	13.6
stacks	6	21	1.17175	1.77325	642.025	15.599
epil	303	236	32.39	37.98	82473.2	281.745
blockers	47	44	3.24711	3.99171	2294.92	33.983
oxford	244	240	16.431	20.859	54546.1	210.933
lsat	1006	5000	171.98	212.486	3.44864e6	1787.39
bones	33	422	70.511	88.375	15448.7	206.655
mice	20	65	7.38875	9.461	1156.67	47.819
kidney	64	58	10.73	16.501	4158.13	78.867
leuk	18	714	20.428	26.59	10531.8	289.549
leukfr	40	714	23.684	31.699	20993.4	257.815