- RadioButtonGroup values for name/required override those of RadioButton

- Fix reactivity when RadioButton is used without group
- Use `readable` when writing is not required
- Use `readonly` to make intent clearer.
- Remove default values for `required` and `name`
  - More consistent with other input types
  - Means that `name` attribute will not be added for no reason

docs/src/COMPONENT_API.json

@@ -4788,7 +4788,7 @@
         {
           "name": "company",
           "kind": "let",
-          "description": "Specify the company name.  \nAlternatively, use the named slot \"company\" (e.g., `<span slot=\"company\">...</span>`)",
+          "description": "Specify the company name.\n\nAlternatively, use the named slot \"company\" (e.g., `<span slot=\"company\">...</span>`)",
           "type": "string",
           "isFunction": false,
           "isFunctionDeclaration": false,
@@ -9463,7 +9463,6 @@
           "kind": "let",
           "description": "Specify a name attribute for the radio button input",
           "type": "string",
-          "value": "\"\"",
           "isFunction": false,
           "isFunctionDeclaration": false,
           "isRequired": false,
@@ -9528,9 +9527,9 @@
           "kind": "let",
           "description": "Set to `true` to require the selection of a radio button",
           "type": "boolean",
-          "value": "false",
           "isFunction": false,
           "isFunctionDeclaration": false,
+          "isRequired": false,
           "constant": false,
           "reactive": false
         },
@@ -9539,9 +9538,9 @@
           "kind": "let",
           "description": "Specify a name attribute for the radio button inputs",
           "type": "string",
-          "value": "\"\"",
           "isFunction": false,
           "isFunctionDeclaration": false,
+          "isRequired": false,
           "constant": false,
           "reactive": false
         },