Fix MSTest analyzer violations breaking main

[Evangelink]

Problem

PR #54766 enabled the Recommended MSTest analyzers as build errors. PR #54758 merged ~2 minutes later, and its Microsoft.TemplateEngine.Authoring.Tasks.IntegrationTests code contains assertions that those analyzers now flag — so main is currently red and every open MSTest migration PR is blocked (their merge builds fail on these same errors).

Fix

Resolve the analyzer violations in the two affected files (no behavior change):

• CommandResultAssertions.MSTest.cs: MSTEST0037 (Assert.IsTrue(a == b) -> Assert.AreEqual; Assert.IsFalse(a == b) -> Assert.AreNotEqual) and MSTEST0023 (Assert.IsTrue(!x) -> Assert.IsFalse(x)).
• LocalizeTemplateTests.cs: MSTEST0037 (Assert.AreEqual(n, x.Length) -> Assert.HasCount(n, x)).

Verification

• ✅ Microsoft.TemplateEngine.Authoring.Tasks.IntegrationTests builds clean (0 warnings / 0 errors) with the analyzers enabled.

This unblocks #54722 #54723 #54724 #54725 #54726 #54729 #54730 #54732 #54759 #54761 #54785 #54787.

[Copilot]

Pull request overview

Fixes MSTest “Recommended” analyzer violations introduced as build errors, restoring clean builds for Microsoft.TemplateEngine.Authoring.Tasks.IntegrationTests and unblocking the ongoing MSTest migration PR stack.

Changes:

• Replace equality-in-boolean asserts with Assert.AreEqual / Assert.AreNotEqual in the MSTest CommandResultAssertions helper.
• Replace negated Assert.IsTrue(!...) patterns with Assert.IsFalse(...).
• Replace AreEqual(expected, array.Length) with Assert.HasCount(expected, array) in localization integration tests.

Show a summary per file

File	Description
test/TemplateEngine/Microsoft.TemplateEngine.Authoring.Tasks.IntegrationTests/LocalizeTemplateTests.cs	Uses Assert.HasCount for file count assertions to satisfy MSTest analyzers.
test/TemplateEngine/Microsoft.TemplateEngine.Authoring.Tasks.IntegrationTests/CommandResultAssertions.MSTest.cs	Updates assertions to analyzer-preferred forms (AreEqual/AreNotEqual/IsFalse) while preserving behavior.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 0

[Evangelink]

/ba-g #54813

The CI failure on this PR is not related to its changes. This PR only modifies two files in Microsoft.TemplateEngine.Authoring.Tasks.IntegrationTests (CommandResultAssertions.MSTest.cs, LocalizeTemplateTests.cs) — MSTest analyzer fixes (Assert.IsTrue(a==b)→AreEqual, IsTrue(!x)→IsFalse(x), AreEqual(n, x.Length)→HasCount). The build compiles cleanly.

The only failing tests are in dotnet.Tests, in the RunFileTests_* family (RunFileTests_BuildCommands.Build_Library_MultiTarget, RunFileTests_CscOnlyAndApi.MSBuildGet_Consistent) — the known-flaky file-based-program build race tracked in #54813 (MSB4025: project file could not be loaded). These have no connection to this PR's Authoring.Tasks analyzer changes.