Fix tests in `Language/LanguageServiceTests.cs`

[andyleejordan]

This file has most of its tests in place, but there are a few that need fixing:

PowerShellEditorServices/test/PowerShellEditorServices.Test/Language/LanguageServiceTests.cs

Lines 323 to 324 in b8ad2c7

	[Fact(Skip = "TODO Fix this test. A possible bug in PSES product code.")]
	public void LanguageServiceFindsReferencesOnCommandWithAlias()

PowerShellEditorServices/test/PowerShellEditorServices.Test/Language/LanguageServiceTests.cs

Lines 337 to 338 in b8ad2c7

	[Fact(Skip = "TODO Fix this test. A possible bug in PSES product code.")]
	public void LanguageServiceFindsReferencesOnAlias()

PowerShellEditorServices/test/PowerShellEditorServices.Test/Language/LanguageServiceTests.cs

Lines 411 to 416 in b8ad2c7

	// TODO: Bring this back when we can use AstVisitor2 again (#276)
	//Assert.Equal(1, symbolsResult.FoundOccurrences.Where(r => r.SymbolType == SymbolType.Configuration).Count());
	//SymbolReference firstConfigurationSymbol = symbolsResult.FoundOccurrences.Where(r => r.SymbolType == SymbolType.Configuration).First();
	//Assert.Equal("AConfiguration", firstConfigurationSymbol.SymbolName);
	//Assert.Equal(25, firstConfigurationSymbol.ScriptRegion.StartLineNumber);
	//Assert.Equal(1, firstConfigurationSymbol.ScriptRegion.StartColumnNumber);