Closes #4711 - Extract VoiceSearchActivity

[NotWoods]

This moves the voice search specific code out of IntentReceiverActivity and into its own class.

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• 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
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features

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• Milestone: Make sure issues finished by this pull request are added to the milestone of the version currently in development.

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[codecov-io]

Codecov Report

Merging #5502 into master will increase coverage by 0.12%.
The diff coverage is 72.22%.

@@             Coverage Diff              @@
##             master    #5502      +/-   ##
============================================
+ Coverage     14.05%   14.18%   +0.12%     
- Complexity      308      316       +8     
============================================
  Files           256      257       +1     
  Lines         10495    10498       +3     
  Branches       1522     1523       +1     
============================================
+ Hits           1475     1489      +14     
+ Misses         8903     8888      -15     
- Partials        117      121       +4

Impacted Files	Coverage Δ	Complexity Δ
...a/org/mozilla/fenix/widget/SearchWidgetProvider.kt	1.36% <0%> (+0.03%)	1 <0> (ø)	⬇️
...nix/home/intent/SpeechProcessingIntentProcessor.kt	100% <100%> (ø)	5 <0> (ø)	⬇️
...n/java/org/mozilla/fenix/IntentReceiverActivity.kt	34.14% <100%> (+0.81%)	4 <0> (-2)	⬇️
...va/org/mozilla/fenix/widget/VoiceSearchActivity.kt	77.77% <77.77%> (ø)	10 <10> (?)

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[sblatz]

This looks great to me 😄

[sblatz]

Rebasing master to see if that fixes the UI test issue.