Create user friendly error if remote oca fails

[wadeking98]

Given the user starts the app without having connection to the oca repository:
if the wallet fails to load the oca index file then the user will be presented with an error message.

Given the user is in the application with a loaded oca index file but no connection to the oca repository:
if the wallet fails to load the branding for a given credential then the user will be prompted with an error message once.

[laygir]

Hey @wadeking98
As a side question, may I ask if there is any guide I can follow on how to set up OCA from a remote repository or any pointers around this would be appreciated, thanks! 🙌