Microsoft.BareMetalInfrastructure: correctly annotate read-only properties with readOnly (#15255)

* Microsoft.BareMetalInfrastructure: correctly annotate read-only properties with readOnly

* Use multi-api and namespace formats for Go SDK like hanaonazure does

Author: lagalbra

specification/baremetalinfrastructure/resource-manager/Microsoft.BareMetalInfrastructure/preview/2020-08-06-preview/baremetalinfrastructure.json

@@ -720,6 +720,7 @@
           "description": "Displayed AzureBareMetal operation information"
         },
         "isDataAction": {
+          "readOnly": true,
           "description": "indicates whether an operation is a data action or not.",
           "type": "boolean"
         }

specification/baremetalinfrastructure/resource-manager/readme.go.md

@@ -5,9 +5,17 @@ These settings apply only when `--go` is specified on the command line.
 ```yaml $(go)
 go:
   license-header: MICROSOFT_MIT_NO_VERSION
+  namespace: baremetalinfrastructure
   clear-output-folder: true
 ```
 
+### Go multi-api
+
+``` yaml $(go) && $(multiapi)
+batch:
+  - tag: package-2020-08-06-preview
+```
+
 ### Tag: package-2020-08-06-preview and go
 
 These settings apply only when `--tag=package-2020-08-06-preview --go` is specified on the command line.