Make it possible to configure lsp-ansible as add-on? t

So that it can work with yamlls.

clients/lsp-ansible.el

@@ -34,6 +34,13 @@
   :link '(url-link "https://github.com/ansible/ansible-language-server")
   :package-version '(lsp-mode . "8.0.1"))
 
+(defcustom lsp-ansible-add-on? nil
+  "Make the lsp client `add-on' so that it works with other language servers.
+E.g., yamlls."
+  :type 'boolean
+  :group 'lsp-ansible
+  :package-version '(lsp-mode . "8.0.1"))
+
 (defcustom lsp-ansible-language-server-command
   '("ansible-language-server" "--stdio")
   "The command that starts the ansible language server."
@@ -234,6 +241,7 @@ Pretty print the content of PARAMS."
                             (lsp-package-path 'ansible-language-server))
                        ,@(cl-rest lsp-ansible-language-server-command))))
   :priority 1
+  :add-on? lsp-ansible-add-on?
   :notification-handlers (ht ("update/ansible-metadata" #'lsp-ansible-update-metadata-handler))
   :activation-fn #'lsp-ansible-check-ansible-minor-mode
   :server-id 'ansible-ls