Fix false positive in MissedSelectOpportunity when foreach body uses await

[Copilot]

The cs/linq/missed-select query incorrectly flagged foreach loops whose first statement used await — loops that cannot be refactored to .Select(...) since LINQ's Select operates on IEnumerable<T> and does not support async lambdas.

// Previously flagged — cannot use Select because of await
foreach (var locator in contactSelectors.Select(s => Page.Locator(s)))
{
    var elements = await locator.CountAsync(); // ← await here blocks Select refactor
    if (elements > 0) { ... }
}

Changes

• csharp/ql/lib/Linq/Helpers.qll: Added exclusion to missedSelectOpportunity — the predicate no longer holds when the first statement's initializer contains an AwaitExpr. Updated doc comment accordingly.

• csharp/ql/test/query-tests/Linq/MissedSelectOpportunity/: New test covering:

  • BAD: plain variable mapping (should be flagged)
  • GOOD: variable mapping whose initializer uses await (should not be flagged)

[hvitved]

Should use inline test expectations, i.e.

postprocess:
 - utils/test/InlineExpectationsTestQuery.ql

This also means adding // $ Alert marker comment in the test file.

[Copilot]

Pull request overview

Adjusts the cs/linq/missed-select query helper logic to avoid flagging foreach loops whose first statement’s initializer contains an await, since these loops can’t be straightforwardly refactored into a synchronous .Select(...) mapping.

Changes:

• Updated missedSelectOpportunity to exclude cases where the first statement’s initializer contains an AwaitExpr.
• Added a new query-test folder for Linq/MissedSelectOpportunity.ql covering one flagged (“BAD”) and one non-flagged (“GOOD”) scenario.
• Added test harness files (options, .qlref, .expected) for the new test.

Show a summary per file

File	Description
csharp/ql/lib/Linq/Helpers.qll	Refines missedSelectOpportunity to ignore await-based initializers; updates the predicate’s doc comment.
csharp/ql/test/query-tests/Linq/MissedSelectOpportunity/options	Adds extractor options/stub project loading for the new test.
csharp/ql/test/query-tests/Linq/MissedSelectOpportunity/MissedSelectOpportunity.qlref	Adds a .qlref pointing at Linq/MissedSelectOpportunity.ql with inline-expectations postprocessing.
csharp/ql/test/query-tests/Linq/MissedSelectOpportunity/MissedSelectOpportunity.expected	Captures the expected single result (only the “BAD” case).
csharp/ql/test/query-tests/Linq/MissedSelectOpportunity/MissedSelectOpportunity.cs	Adds “BAD” and “GOOD” C# examples to validate the updated behavior.

Copilot's findings

• Files reviewed: 5/5 changed files
• Comments generated: 2