feat: Add local file provider and wire everything up in the file module (#7134)

packages/core-flows/src/file/steps/upload-files.ts

@@ -6,7 +6,7 @@ type UploadFilesStepInput = {
   files: {
     filename: string
     mimeType: string
-    content: Blob
+    content: string
   }[]
 }
 

packages/core-flows/src/file/workflows/upload-files.ts

@@ -6,7 +6,7 @@ type WorkflowInput = {
   files: {
     filename: string
     mimeType: string
-    content: Blob
+    content: string
   }[]
 }