h5. Description

Search fields provided by UIToolkit (Asset Manager and Package Manager window) does not protect against typing infinite amount of characters. This lead to the editor freezing.
h5. How to reproduce:

1. Open Package Manager window
2. In the search bar, type some text then repeat this sequence a couple of times: Ctrl + a, Ctrl + c, Ctrl + v

h5. Actual result:

macOS: At some point, macOS beachball appears spinning and Unity editor is frozen.

Windows: The search text field has no validation and the Editor will start constantly repainting if the Package Manager window is visible (see video and screenshot attached).
h5. Expected result:

Option: show a Search String Character Limit Exceeded like in the Project browser window (screenshot attached).
h5. Environment

Reproducible with: 2023.2.2f1, 2023.3.0a16
Not reproducible with: 2022.3.14f1, 2023.1.20f1 (Old Packman) !image.png|thumbnail!