feat(SettingIcon): Add clear symbols button

[TheSmuks]

Description

Added a button to clear selected symbols in Global Settings modal.

Motivation and Context

Why is this change required? What problem does it solve? This is useful when users frequently experiment with different symbols and need to change the entire symbol list. Now they can clear the symbol list with just one click instead of manually deselecting each symbol.

How Has This Been Tested?

1. Add symbols to the list
2. Save changes
3. Use the "Clear selection" button
4. Save changes
5. Check if the list is empty

Screenshots (if appropriate):

[chrisleekr]

@TheSmuks

Thank you so much for your contribution.

I just added validation to ensure at least one symbol is added to the list.

:)