Increase ddg test coverage, fix typos

[everett980]

Which problem is this PR solving?

• When implementing DDG some tests were skipped to meet a deadline.

Short description of the changes

• This PR brings coverage of DDG-related files up to 100%

[codecov]

Codecov Report

Merging #468 into master will increase coverage by 2.78%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #468      +/-   ##
=========================================
+ Coverage   89.41%   92.2%   +2.78%     
=========================================
  Files         192     192              
  Lines        4479    4477       -2     
  Branches     1073    1071       -2     
=========================================
+ Hits         4005    4128     +123     
+ Misses        428     307     -121     
+ Partials       46      42       -4

Impacted Files	Coverage Δ
...c/model/ddg/GraphModel/getDerivedViewModifiers.tsx	100% <ø> (+100%)	⬆️
...omponents/DeepDependencies/Header/NameSelector.tsx	100% <ø> (+12.5%)	⬆️
...kages/jaeger-ui/src/model/ddg/visibility-codec.tsx	100% <ø> (ø)	⬆️
...components/DeepDependencies/Graph/getSetOnEdge.tsx	100% <100%> (+60%)	⬆️
...aeger-ui/src/components/DeepDependencies/index.tsx	100% <100%> (+26.82%)	⬆️
...er-ui/src/model/ddg/sample-paths.test.resources.js	100% <100%> (ø)	⬆️
...ts/DeepDependencies/Graph/DdgNodeContent/index.tsx	100% <100%> (+64.7%)	⬆️
...s/DeepDependencies/Header/LayoutSettings/index.tsx	100% <100%> (+84.21%)	⬆️
...ui/src/components/DeepDependencies/Graph/index.tsx	100% <100%> (+33.33%)	⬆️
...eViewer/TimelineHeaderRow/TimelineViewingLayer.tsx	88.13% <0%> (-1.7%)	⬇️
... and 9 more

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