feat: add cursor param to test results endpoint

[ajay-sentry]

This PR adds the ability to input a "cursor" into the test_results endpoint so we can try to implement pagination on the Sentry UI.

Closes https://linear.app/getsentry/issue/CCMRG-1309/figure-out-pagination-for-all-endpoints

Still need to figure out how this would work on the infinite results hook but at the very least we can continually fetch pages on postman. Below are some screenshots of me fetching subsequent pages on postman using the cursor attribute

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

:white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...ntry/codecov/endpoints/TestResults/test_results.py	75.00%	1 Missing :warning:

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #93525       +/-   ##
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+ Coverage   72.17%   84.19%   +12.02%     
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  Files       10295    10311       +16     
  Lines      593834   594303      +469     
  Branches    23044    23044               
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+ Hits       428589   500390    +71801     
+ Misses     164796    93464    -71332     
  Partials      449      449