feat: add observable queue

[amondnet]

Describe the changes proposed in this Pull Request.

Fixes #887

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Pull Request Checklist

• [x] If the changes are being made to code, ensure the version in pubspec.yaml is updated.
• [x] Increment the major/minor/patch/patch-count, depending on the complexity of change
• [x] Add the necessary unit tests to ensure the coverage does not drop
• [x] Update the Changelog to include all changes made in this PR, organized by version
• [x] Run the melo run set_version command from the root directory
• [x] Include the necessary reviewers for the PR
• [ ] Update the docs if there are any API changes or additions to functionality

[codecov[bot]]

Codecov Report

Merging #892 (03e2d15) into master (13b7e6d) will increase coverage by 0.08%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #892      +/-   ##
==========================================
+ Coverage   98.96%   99.04%   +0.08%     
==========================================
  Files          55       56       +1     
  Lines        1924     2105     +181     
==========================================
+ Hits         1904     2085     +181     
  Misses         20       20              

Flag	Coverage Δ
flutter_mobx	100.00% <ø> (ø)
mobx	98.70% <100.00%> (+0.17%)	:arrow_up:
mobx_codegen	100.00% <ø> (ø)

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

Impacted Files	Coverage Δ
...c/api/observable_collections/observable_queue.dart	100.00% <100.00%> (ø)

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[pavanpodila]

closing this as its gone stale