Fix "pattern" UI Component validation

[bap14]

Description

Convert param string to regular expression using constructor and test on the RegExp object.

Fixed Issues (if relevant)

1. Pattern Validation via UI Component Fails to Interpret String as RegEx Pattern #9919: Pattern Validation via UI Component Fails to Interpret String as RegEx Pattern

Manual testing scenarios

1. Create a custom UI Component form

2. Add a validation item to an input field

3. Specify a pattern validation rule with a custom regular expression pattern. E.g.

    <item name="validation" xsi:type="array">
        <item name="required-entry" xsi:type="boolean">true</item>
        <item name="no-whitespace" xsi:type="boolean">true</item>
        <item name="pattern" xsi:type="string">^[a-zA-Z][a-zA-Z0-9_.-]{3,}$</item>
    </item>
   

4. View form in admin browser and enter valid and invalid values (e.g. 3sdf and asd3)

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)