Issue #7194: Create a Browser Containers component

[gabrielluong]

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Fixes #7194. For ContextualIdentityStorage.addContextualIdentity, I will note that I followed the API of contextualIdentities.create() since this is what most web extensions care about.

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

After merge

• Milestone: Make sure issues closed by this pull request are added to the milestone of the version currently in development.
• Breaking Changes: If this is a breaking change, please push a draft PR on Reference Browser to address the breaking issues.

[gabrielluong]

Ah seems like CI doesn't like the component naming:

RuntimeError: Treeherder group and symbol names must not be longer than 25 characters: feature-contextualidentities(BN) (see https://github.com/taskcluster/taskcluster-treeherder/blob/master/schemas/task-treeherder-config.yml)

[gabrielluong]

• I am going to move this over to a browser component after talking with @jonalmeida since this is a component of a browser over a feature on its own.

[gabrielluong]

Ah seems like CI doesn't like the component naming:

RuntimeError: Treeherder group and symbol names must not be longer than 25 characters: feature-contextualidentities(BN) (see https://github.com/taskcluster/taskcluster-treeherder/blob/master/schemas/task-treeherder-config.yml)

• Also, considering renaming this to browser-containers to get over the RuntimeError.

[gabrielluong]

• We might want to consider moving to coroutines similar to Move TopSitesStorage to Coroutines #7071

[codecov]

Codecov Report

Merging #7195 into master will decrease coverage by 0.21%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #7195      +/-   ##
============================================
- Coverage     77.35%   77.14%   -0.22%     
+ Complexity     5056     4871     -185     
============================================
  Files           674      654      -20     
  Lines         24736    23399    -1337     
  Branches       3655     3497     -158     
============================================
- Hits          19134    18050    -1084     
+ Misses         4089     3917     -172     
+ Partials       1513     1432      -81     

Impacted Files	Coverage Δ	Complexity Δ
...ture/addons/ui/UnsupportedAddonsAdapterDelegate.kt
.../mozilla/components/lib/nearby/NearbyConnection.kt
...ts/feature/addons/update/db/UpdateAttemptEntity.kt
...a/components/feature/addons/ui/CustomViewHolder.kt
...feature/addons/migration/SupportedAddonsChecker.kt
...ozilla/components/feature/addons/AddonsProvider.kt
.../mozilla/components/feature/addons/AddonManager.kt
...ure/addons/update/GlobalAddonDependencyProvider.kt
...a/components/feature/addons/update/AddonUpdater.kt
...lla/components/feature/addons/worker/Extensions.kt
... and 11 more

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[gabrielluong]

bors r=pocmo

[bors]

Build succeeded:

• complete-push