Fix code lens disappear after non-test class issue

[st0012]

Motivation

Currently we always pop a class from the stack when we run after_class, but only push test classes when we run on_class. This means that if we encounter a non-test class in the middle of a test class, we will mistakenly pop the test class from the stack.

Implementation

This commit fixes this by pushing a non-test class to the stack too. But while doing so, we also need to check if on_def is in a test class or not.

Automated Tests

Added a new case for it.

Manual Tests

Currently, the test_after_request_hook in HoverExpectationsTest doesn't have code lens due to the issue I described. It should appear when switched to this branch.

[github-actions]

Benchmark results in seconds (slowest at top)

          textDocument/completion average: 0.301594 std_dev: 0.006206
          textDocument/diagnostic average: 0.048505 std_dev: 0.0107
      textDocument/selectionRange average: 0.004118 std_dev: 0.000549
   textDocument/documentHighlight average: 0.002113 std_dev: 0.000153
        textDocument/documentLink average: 0.00203 std_dev: 0.000158
            textDocument/codeLens average: 0.001998 std_dev: 0.000188
 textDocument/semanticTokens/full average: 0.001927 std_dev: 0.00022
      textDocument/documentSymbol average: 0.001923 std_dev: 0.000111
        textDocument/foldingRange average: 0.001849 std_dev: 0.000127
textDocument/semanticTokens/range average: 0.000941 std_dev: 8.2e-05
               codeAction/resolve average: 0.000764 std_dev: 8.6e-05
               textDocument/hover average: 0.000707 std_dev: 8.0e-05
           textDocument/inlayHint average: 0.000697 std_dev: 4.6e-05
    textDocument/onTypeFormatting average: 0.000129 std_dev: 5.0e-05
          textDocument/formatting average: 8.1e-05 std_dev: 0.000333
          textDocument/codeAction average: 4.7e-05 std_dev: 3.3e-05


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Comparison with main branch:

 textDocument/semanticTokens/full unchanged
textDocument/semanticTokens/range unchanged
      textDocument/documentSymbol unchanged
        textDocument/foldingRange unchanged
          textDocument/formatting unchanged
          textDocument/diagnostic unchanged
        textDocument/documentLink unchanged
           textDocument/inlayHint unchanged
      textDocument/selectionRange unchanged
   textDocument/documentHighlight unchanged
               textDocument/hover unchanged
          textDocument/codeAction unchanged
    textDocument/onTypeFormatting unchanged
               codeAction/resolve unchanged
          textDocument/completion unchanged
            textDocument/codeLens unchanged