feat: add placeholder to datagrid string filter

[steve-haar]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)
• [ ] If applicable, have a visual design approval

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [x] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Documentation content changes
• [ ] clarity.design website / infrastructure changes
• [ ] Other... Please describe:

What is the current behavior?

The datagrid filter input did not have any visual label.

Issue Number: https://jira.eng.vmware.com/browse/VPAT-687

What is the new behavior?

Now, there is a visual placeholder in the datagrid filter

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

[vmwclabot]

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• Commit 70ef52b39cce3ad34ff0811fd1b85d4174c9f924 must be signed by info@stevehaar.com