Better error feedback when editing bookmarks in settings

[EmmanuelMess]

Describe the bug
Error feedback for editing bookmarks in settings is nonexistent.

To Reproduce
Steps to reproduce the behavior:

1. Got to settings
2. Edit a bookmark
3. Introduce a broken path
4. No error appears in UI
5. Sometimes, pressing "EDIT" is allowed, but a toast appears afterwards

Expected behavior
A WarningTextEdit or a field in the dialog should be used to tell the user the errors.

Screenshots

Smartphone (please complete the following information):

• Device: Pixel 9 emulator
• OS: API 35
• Rooted: No
• Version: release/4.0

Related #4681.

[alihrhera]

In your opinion, which version looks better, or which one do you prefer?

or this

[EmmanuelMess]

@alihrhera please use the current WarnableTextInputValidator class and warn for each filed their particular warning/error.