Filter out project early if it doesn't have any formattable documents

Improves the runtime in large solutions when a small number of files is
included (`--include`). This is a common use-case for developers to
lint/format only modified files in their branch.

In a solution with about 80 projects, this improves the runtime by about
50% when `--include SomeProject/SomeFile.cs` is specified.

Related issues: #1378 and
#757

Author: erdalsivri

src/Analyzers/AnalyzerFormatter.cs

@@ -283,6 +283,11 @@ internal static async Task<ImmutableDictionary<ProjectId, ImmutableArray<Diagnos
                 {
                     continue;
                 }
+                // Skip if the project does not contain any of the formattable paths.
+                if (!project.Documents.Any(d => d.FilePath is not null && formattablePaths.Contains(d.FilePath)))
+                {
+                    continue;
+                }
 
                 var analyzers = ImmutableArray.CreateBuilder<DiagnosticAnalyzer>();