Remove Turing integration tests

[penelopeysm]

Companion to TuringLang/Turing.jl#2393

Closes #703

Breaking changes in TestUtils.DEMO_MODELS

• What was originally demo_assume_observe_literal has been renamed to demo_assume_multivariate_observe_literal to avoid disambiguation with new model
• demo_assume_literal_dot_observe renamed to demo_assume_dot_observe_literal to match the naming pattern of the other models
• Added a new demo_assume_observe_literal, which is a univariate assume

@model function demo_assume_observe_literal()
    # univariate `assume` and literal `observe`
    s ~ InverseGamma(2, 3)
    m ~ Normal(0, sqrt(s))
    1.5 ~ Normal(m, sqrt(s))
    2.0 ~ Normal(m, sqrt(s))

    return (; s=s, m=m, x=[1.5, 2.0], logp=getlogp(__varinfo__))
end

TODO

• Update CI
• Reimplement loglikelihoods.jl tests inside DPPL tests They are already inside pointwise_logdensities.jl
• Implement a function to generate a Chain by sampling from the prior of a Model (thus avoiding calls to e.g. sample(model, NUTS(), ...))
• Look into reimplementing model.jl tests inside DPPL tests
• Clone demo_static_transformations inside DemoModels
• Bump version

[coveralls]

Pull Request Test Coverage Report for Build 12087688415

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 22 of 22 (100.0%) changed or added relevant lines in 1 file are covered.
• 70 unchanged lines in 7 files lost coverage.
• Overall coverage decreased (-1.7%) to 84.716%

---

Files with Coverage Reduction	New Missed Lines	%
ext/DynamicPPLForwardDiffExt.jl	1	77.78%
src/sampler.jl	1	94.55%
src/contexts.jl	2	77.04%
src/logdensityfunction.jl	2	70.37%
src/abstract_varinfo.jl	5	78.62%
src/model_utils.jl	10	19.64%
src/varinfo.jl	49	82.0%

Totals
Change from base Build 12083280383:	-1.7%
Covered Lines:	3553
Relevant Lines:	4194

---

💛 - Coveralls