Make text inside siteInfo__wrapper unselectable

[luixxiul]

Closes #8650

Auditors:

Test Plan:

1. Open https://brave.com
2. Click the lock icon
3. Make sure you cannot select the text on the dialog

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Test Plan:

[bbondy]

++