Add show_stack(::AbstractContext)

[penelopeysm]

The docstring says it all. Basically this is a method I've been wanting for ages and I finally decided to implement it after realising that GibbsContext contains a complete VarInfo inside it and it's impossible to parse the output of @show context. Obviously I could just run this myself every time I needed it, but I thought it might be useful enough to be added to DynamicPPL itself, hence the PR.

Not even sure if this warrants a patch bump + release, opinions are welcome.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 84.92%. Comparing base (e75fd1e) to head (db1f96c).

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

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #909      +/-   ##
==========================================
- Coverage   85.01%   84.92%   -0.09%     
==========================================
  Files          35       35              
  Lines        3924     3928       +4     
==========================================
  Hits         3336     3336              
- Misses        588      592       +4     

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[coveralls]

Pull Request Test Coverage Report for Build 14815463313

Details

• 0 of 4 (0.0%) changed or added relevant lines in 1 file are covered.
• 17 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.3%) to 84.76%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/contexts.jl	0	4	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/model.jl	1	85.83%
src/threadsafe.jl	16	55.05%

Totals
Change from base Build 14706709520:	-0.3%
Covered Lines:	3326
Relevant Lines:	3924

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 14815463313

Details

• 0 of 4 (0.0%) changed or added relevant lines in 1 file are covered.
• 17 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.09%) to 85.015%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/contexts.jl	0	4	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/model.jl	1	85.83%
src/threadsafe.jl	16	55.05%

Totals
Change from base Build 14706709520:	-0.09%
Covered Lines:	3336
Relevant Lines:	3924

---

💛 - Coveralls

[mhauru]

Since the docstring has an example, could that be a doctest?

I wonder if this should be a show(::AbstractContext, ::MIME"text/plain") method. Maybe it omits too much, and the -> thing is too non-standard?

Happy to release this with a patch bump or wait for the next release.

[penelopeysm]

I think making this the default show method is a bit too dangerous, it's sometimes useful to see e.g. the sampler in SamplingContext or the values in Condition/FixedContext.
I'll add tests...