Package Manager search text field has no validation and leads to Editor freezes

How to reproduce:
1. Open Package Manager
2. In the search text field enter numerous characters

Actual result: The search text field has no validation and the Editor will start constantly repainting if the Package Manager window is visible
Expected result: The search field text is truncated as with the old text field

Reproducible with: 2023.2.2f1, 2023.3.0a16
Not reproducible with: 2022.3.14f1, 2023.1.20f1 (Old Packman)