Add sdk-test module to hold robolectric shadow classes.

[pengdev]

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Pull request checklist:

• [ ] Briefly describe the changes in this PR.
• [ ] Include before/after visuals or gifs if this PR includes visual changes.
• [ ] Write tests for all new functionality. If tests were not written, please explain why.
• [ ] Optimize code for java consumption (@JvmOverloads, @file:JvmName, etc).
• [ ] Add example if relevant.
• [ ] Document any changes to public APIs.
• [ ] Apply changelog label ('breaking change', 'bug :beetle:', 'build', 'docs', 'feature :green_apple:', 'performance :zap:', 'testing :100:') or use the label 'skip changelog'
• [ ] Add an entry inside this element for inclusion in the mapbox-maps-android changelog: <changelog></changelog>.
• [ ] If this PR is a v10.[version] release branch fix / enhancement, merge it to main firstly and then port to v10.[version] release branch.

Fixes: < Link to related issues that will be fixed by this pull request, if they exist >

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