Feat: Add android example of MNIST inference

[Scramjet911]

Checklist

• [x] Confirmed that run-checks all script has been executed.
• [ ] Made sure the book is up to date with changes in this PR.

Related Issues/PRs

Discussed this in Issue #2208, added the example.

Changes

Better examples to show usage of Burn and cross platform capabilities

Testing

I ran the app with multiple inputs off the internet and it worked fine. I have not modified the android tests. Will delete or fix them as required, since I don't think they'll run with the current testing infra?

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.88%. Comparing base (96a2340) to head (3a235e6). Report is 592 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2221   +/-   ##
=======================================
  Coverage   85.88%   85.88%           
=======================================
  Files         707      707           
  Lines       89805    89805           
=======================================
+ Hits        77130    77131    +1     
+ Misses      12675    12674    -1     

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[github-actions[bot]]

This PR has been marked as stale because it has not been updated for over a month

[antimora]

I recommend having this example in a separate repo.