[18.0][MIG] web_widget_pattern: Migration to 18.0

[sensiblecs]

No description provided.

[hbrunn]

Further testing reveals several problems:

• the pattern doesn't work when setting the pattern parameter on a field in python code
  You need to patch Field.parseFieldNode for this:

  +import {Field} from  "@web/views/fields/field";
  ...
  +patch(Field, {
  +    parseFieldNode(node, models, modelName, viewType, jsClass) {
  +        const fieldInfo = super.parseFieldNode(...arguments);
  +        fieldInfo.pattern = models[modelName].fields[fieldInfo.name].pattern;
  +        return fieldInfo;
  +    }
  +});

  and change extractProps accordingly
• function base#fields_get should check for attributes being falsy, not None
• function base#_get_view_field_attributes doesn't exist any more, so this override should be removed
• the autocomplete component now inherits from Char, so this override should be removed too
• please fix the tests

[hbrunn]

superseded by #3511