Closes #2332: Add WebAppManifestParser for creating WebAppManifest from JSON.

[pocmo]

Pull Request checklist

• Quality: This PR builds and passes detekt/ktlint checks (A pre-push hook is recommended)
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry or does not need one
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features

[codecov]

Codecov Report

Merging #2339 into master will increase coverage by 0.1%.
The diff coverage is 73.33%.

@@             Coverage Diff             @@
##             master    #2339     +/-   ##
===========================================
+ Coverage     83.42%   83.52%   +0.1%     
- Complexity     2637     2659     +22     
===========================================
  Files           320      321      +1     
  Lines         10933    11007     +74     
  Branches       1585     1591      +6     
===========================================
+ Hits           9121     9194     +73     
+ Misses         1153     1148      -5     
- Partials        659      665      +6

Impacted Files	Coverage Δ	Complexity Δ
...ponents/browser/session/manifest/WebAppManifest.kt	100% <100%> (+85.71%)	13 <0> (+12)	⬆️
...s/browser/session/manifest/WebAppManifestParser.kt	72.6% <72.6%> (ø)	2 <2> (?)
...illa/components/service/glean/LabeledMetricType.kt	88.67% <0%> (+0.74%)	24% <0%> (-1%)	⬇️
...illa/components/service/glean/BooleanMetricType.kt	95.23% <0%> (+1.9%)	17% <0%> (+9%)	⬆️

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[Amejia481]

LGTM ✅

[pocmo]

Okay, updated PR. :)