[WB-8243] Add captions to Molecules

[dmitryduev]

Fixes WB-8243

Description

Add the ability to set captions on wandb.Molecule objects.

Testing

How was this PR tested?

Checklist

• Name PR "[WB-NNNN][WB-MMMM] Add support for..." similar to entries in CHANGELOG.md
• Include reference to internal ticket "Fixes WB-NNNN" (and github issue "Fixes #NNNN" if applicable)

[codecov]

Codecov Report

Merging #3173 (cbe56b8) into master (67b8208) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3173      +/-   ##
==========================================
+ Coverage   79.03%   79.06%   +0.03%     
==========================================
  Files         210      210              
  Lines       27658    27659       +1     
==========================================
+ Hits        21859    21869      +10     
+ Misses       5799     5790       -9     

Flag	Coverage Δ
functest	57.17% <33.33%> (+0.05%)	⬆️
unittest	68.91% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
wandb/sdk/wandb_run.py	87.87% <ø> (+0.26%)	⬆️
wandb/sdk/data_types.py	84.34% <100.00%> (+0.01%)	⬆️
wandb/sdk/lib/sock_client.py	92.85% <0.00%> (-1.79%)	⬇️
wandb/filesync/step_prepare.py	92.85% <0.00%> (-1.43%)	⬇️
wandb/sdk/internal/stats.py	67.22% <0.00%> (-0.56%)	⬇️
wandb/sdk/internal/sender.py	91.44% <0.00%> (-0.28%)	⬇️
wandb/sdk/lib/git.py	76.35% <0.00%> (ø)
wandb/util.py	74.05% <0.00%> (+0.48%)	⬆️
wandb/sdk/internal/meta.py	90.74% <0.00%> (+3.08%)	⬆️
... and 1 more

[captain-pool]

LGTM

[tssweeney]

LGTM - nice catch. Did you test this in the UI? Would be good to close the loop to make sure this is not only a code-correctness fix, but also respected in the media panel.

[dmitryduev]

@tssweeney: @captain-pool tested that and it's actually broken :)