Add external import sources, work history, screening fields and Phase 1 docs

- New ExternalImportSource and ExternalWorkHistoryEntry models, controller and migrations
- Screening fields on external profile imports
- Admin and provider profile views, routes and workflow tests updated
- Phase 1 validation, route inventory, gap report template and roadmap docs
- Add the Google Sheets work-order parser tool (tools/google-sheets-wo-parser)

app/Models/ProviderProfile.php

@@ -39,6 +39,16 @@ class ProviderProfile extends Model
         return $this->hasMany(ExternalProfileImport::class);
     }
 
+    public function externalImportSources(): HasMany
+    {
+        return $this->hasMany(ExternalImportSource::class);
+    }
+
+    public function externalWorkHistoryEntries(): HasMany
+    {
+        return $this->hasMany(ExternalWorkHistoryEntry::class);
+    }
+
     public function attachments(): MorphMany
     {
         return $this->morphMany(Attachment::class, 'attachable');