Pull Request Title

Display new SecondBrain Icon if SecondBrain URL is set https://github.com/stakwork/sphinx-mac/issues/313

This pull request addresses the Display new SecondBrain Icon if SecondBrain URL is set https://github.com/stakwork/sphinx-mac/issues/313.

Display icon if second_brain_url is set in tribes settings, similar to app_url
onClick, should do the exact same functionality as tapping the 9 squares app_url

Assets:
- Added secondBrainIcon
ChatHeaderViewDelegate:
- Updated the delegate protocol to include didClickSecondBrainAppButton method
ChatTopView
- Added the toggleSecondBrainAppIcon method and called it in updateViewOnTribeFetch method
WebAppViewController:
- Updated the instantiate method to accept isAppUrl which is used to toggle between the appUrl and secondBrainUrl. By default it is true which is used for appUrl
NewChatViewController:
- Updated the ChatHeaderViewDelegate conformance to include the didClickSecondBrainAppButton method
WindowsManager:
- Updated the showWebAppWindow to accept isAppUrl which is used to toggle between the appUrl and secondBrainUrl.
Chat:
- Added the hasSecondBrainApp which returns a bool to indicate if it has the secondbrain url
ChatHeaderView xib
- Added the button for the secondBrainButton in the stack view and connect to the file
ChatHeaderView
- Added IBOutlet of secondBrainButton in ChatHeaderView
- Ensure the cursor pointer of the button is pointingHand
- Hides the secondBrainButton in the setupDisabledMode method
- Added the toggleSecondBrainAppIcon to toggle the button when it exist
- Added the secondBrainAppButtonClicked method that calls the didClickSecondBrainAppButton using the delegate