web_tree_dynamic_colored_field: Parse field options with pyeval

The options in <field> attributes are parsed as python expressions:
d18976d748/addons/web/static/src/js/services/data_manager.js (L273)

And the options in <button> are parsed as json...
d18976d748/addons/web/static/src/js/services/data_manager.js (L411)

This code only support the <field> element because I'm not sure there
is a use for the <button> element.

web_tree_dynamic_colored_field/static/src/js/web_tree_dynamic_colored_field.js

@@ -56,7 +56,11 @@ odoo.define('web_tree_dynamic_colored_field', function (require) {
             }
             // apply <field>'s own `options`
             if (!node.attrs.options) { return; }
-            var nodeOptions = JSON.parse(node.attrs.options);
+            if (node.tag !== 'field') { return; }
+            var nodeOptions = node.attrs.options;
+            if (!_.isObject(nodeOptions)) {
+                nodeOptions = pyeval.py_eval(nodeOptions);
+            }
             this.applyColorizeHelper($td, nodeOptions, node, 'fg_color', 'color', ctx);
             this.applyColorizeHelper($td, nodeOptions, node, 'bg_color', 'background-color', ctx);
         },