Call indexProgressManager.indexStatusDidChange when workspaces in the SourceKitLSPServer are modified

`IndexProgressManager` iterates over all workspaces in the SourceKitLSPServer. Modifying workspaces might thus update the index progress status.

Author: ahoppen

Sources/SourceKitLSP/SourceKitLSPServer.swift

@@ -507,6 +507,9 @@ public actor SourceKitLSPServer {
   private var workspacesAndIsImplicit: [(workspace: Workspace, isImplicit: Bool)] = [] {
     didSet {
       uriToWorkspaceCache = [:]
+      // `indexProgressManager` iterates over all workspaces in the SourceKitLSPServer. Modifying workspaces might thus
+      // update the index progress status.
+      indexProgressManager.indexStatusDidChange()
     }
   }